Bicyclic nucleosides and nucleotides as therapeutic agents

ABSTRACT

The present disclosure relates to the use and methods of manufacture of bicyclic nucleosides and nucleotides for the treatment and prevention of infectious and proliferative diseases, including microbial infections and cancer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent Ser. No. 13/348,429,filed Jan. 11, 2012, which is a continuation of U.S. Pat. No. 8,119,607,filed Jul. 1, 2009, which claims the benefit of U.S. ProvisionalApplication Ser. No. 61/077,972, filed Jul. 3, 2008, each of which ishereby incorporated by reference.

STATEMENT CONCERNING GOVERNMENT INTEREST

Not applicable.

SEQUENCE LISTINGS

Not applicable.

BACKGROUND OF THE DISCLOSURE

Nucleoside drugs have been used clinically for decades for the treatmentof viral infections and proliferative disorders such as cancer. Mostnucleoside drugs (analogues) are classified as antimetabolites. Afterthey enter cells, nucleoside analogues are phosphorylated successivelyto nucleotide 5′-mono-phosphates, 5′-di-phosphates, and5′-tri-phosphates. In some cases, nucleotide tri-phosphates, e.g.,3′-azido-3′-deoxythymidine tri-phosphate (AZT, an anti-humanimmunodeficiency virus (HIV) drug) and arabinosylcytosine tri-phosphate(cytarabine, an anticancer drug), are the active chemical entities thatinhibit DNA or RNA synthesis through competitive inhibition ofpolymerases and subsequent incorporation of modified nucleotides intoDNA or RNA sequences. In a few cases, nucleoside analogues exert effectsas their 5′-monophosphate or 5′-diphosphate. For instance,5-fluoro-2′-deoxyuridine 5′-mono-phosphate (an anticancer drug) and2′,2′-difluoro-2′-deoxycytidine 5′-di-phosphate (an anticancer drug)have been shown to inhibit thymidylate synthase and ribonucleotidereductase, respectively. Although unphosphorylated nucleoside analoguesthemselves may act as adenosine kinases inhibitors and adenosinereceptor ligands, currently, clinically-useful nucleoside drugsprimarily depend on cellular activation by nucleoside and nucleotidekinases.

Viral infections are a major threat to human health and account for manyserious infectious diseases. The most notable viruses are theblood-borne viruses (BBV), which include hepatitis C virus (HCV),hepatitis B virus (HBV) and HIV, which are all linked by their mode oftransmission, i.e., through blood or bodily fluids.

The Flaviviridae is a group of positive single-stranded RNA viruses witha genome size from 9-15 kilobases (kb). The Flaviviridae consist ofvarious genera including Flavivirus and Hepacivirus. Flavivirus includesDengue, Japanese Tick-Borne, and Yellow Fever viruses. Apart from thesemajor groups, there are some additional Flavivirus that areunclassified. Hepacivirus include only one species, the Hepatitis Cvirus, which is composed of many genotypes and subtypes.

Hepatitis C virus is a major cause of viral hepatitis and has infectedmore than 200 million people worldwide. Hepatitis C virus has apositive-strand RNA genome enclosed in a nucleocapsid and lipidenvelope. The HCV genome is approximately 9.6 kb in length and encodes apolyprotein of about 3,000 amino acids (Dymock et al. AntiviralChemistry & Chemotherapy 2000, 11, 79). Current treatment for HCVinfection is restricted to immunotherapy with interferon-α alone or incombination with ribavirin, a nucleoside analogue. However, thistreatment is effective in only about half the patient population.Recently, several PCT patent applications (WO 99/43691, WO 01/32153, WO01/60315, WO 01/79246, WO 01/90121, WO 01/92282, WO 02/18404, WO02/057287, and WO 02/057425) have described nucleoside analogues asanti-HCV agents in in vitro assays.

Hepatitis B virus has acutely infected almost a third of the humanpopulation, and about 5% of the infected are chronic carriers of thevirus (Delaney W E et al., Antiviral Chemistry & Chemotherapy 2001, 12,1-35). Chronic HBV infection causes liver damage that frequentlyprogresses to cirrhosis and/or liver cancer later in life. Despite theavailability and widespread use of effective vaccines and chemotherapy,the number of chronic HBV carriers approaches 400 million worldwide.

Human immunodeficiency virus causes progressive degeneration of theimmune system, leading to the development of AIDS. A number of drugshave been used clinically to treat AIDS, including reverse transcriptaseinhibitors and protease inhibitors. Currently, combination therapies areused widely for the treatment of AIDS in order to reduce drugresistance. Despite the progress in the development of anti-HIV drugs,AIDS is still one of the leading epidemic diseases.

Apart from the BBV's discussed above, certain other acute viralinfections also pose a great threat to human life, including infectionsof Herpes Simplex virus (HSV), cytomegalovirus (CMV), influenza viruses,West Nile virus, Coronaviruses, causing for example, severe acuterespiratory syndrome (SARS), Variola virus (causing smallpox),Epstein-Barr virus (EBV), Varicella zoster virus (VZV), and Humanrespiratory syncytial virus (RSV). Accordingly, the broad range ofassociated infectious diseases and the propensity for viral mutationhighlight the continued need for the development of different antiviraldrugs.

Bacterial infections have long been the source of many infectiousdiseases. The widespread use of antibiotics has produced many newstrains of life-threatening antibiotic resistant bacteria. Fungalinfections are another type of infectious disease, some of which arealso life-threatening. There is an ever increasing demand for thetreatment of bacterial and fungal infections. As such, antimicrobialdrugs based on new mechanisms of action are especially important.

Proliferative disorders (for example, cancer) are some of the mostlife-threatening diseases today and have been investigated intensivelyfor decades. Cancer is currently the second leading cause of death inthe United States, and over 500,000 people die annually from thisproliferative disorder. All of the various nucleated cell types of thebody can be transformed into benign or malignant tumour cells.Transformation of normal cells into cancer cells is a complex processand is not understood fully. Cancer treatment includes primarilysurgery, radiation therapy, and chemotherapy. While chemotherapy can beused to treat many types of cancer, surgery and radiation therapy arelimited to certain cancers at certain sites of the body. There are anumber of anticancer drugs widely used clinically. Among them arealkylating agents, such as cisplatin, and antimetabolites, such as5-fluorouracil and gemcitabine. Although surgery, radiation therapy, andchemotherapy are available to treat cancer patients, there is no curefor cancer at the present time. Cancer research remains one of the mostimportant focuses of medical and pharmaceutical organizations.

Numerous examples exist in the literature for the synthesis of a varietyof modified nucleosides (Chemistry of Nucleosides and Nucleotides, Vol.1 (1988), Vol. 2 (1991), Vol. 3 (1994), edited by Leroy B. Townsend,Plenum Press). However, there are certain classes of nucleosidecompounds that have not been explored fully for their antiviral andanti-proliferative activities. One such class is the bicyclicnucleosides.

Similarly, cycloalkyl-substituted bicyclic nitrogenous base analoguesare being employed as protein kinase inhibitors to combat uncontrolledcell growth, such as is described in U.S. Patent Application PublicationNo. 2007/0203143.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a compound of formula I isprovided for use in treating or preventing a hepatitis C viral infectionin a subject suffering from or at risk of a hepatitis C viral infectioncomprising in vivo production of a therapeutically effective metaboliteof the compound of formula I, wherein the metabolite has anintracellular half-life of greater than about 10 hours, and whereinformula I includes:

wherein

the defines the active pharmaceutical ingredient as a D- or L-nucleosideor nucleotide; A is selected from the group consisting of —O—, —S—,—CH₂—, —CHF—, —CF₂—, and —NR—; R^(1′), R², R^(2′), R³, R^(3′), andR^(4′) are independently selected from the group consisting of —H,halogen, —OH, —HOH, —NHNH₂, —N₃, —CN, —OCOCHNC(CH₃)₂, —COOH, —CONH₂,—C(S)NH₂, —COOR, —R, —OR, —SR, —SR, —NHR, and —NR₂, or R² and R^(2′)together or R³ and R^(3′) together represents ═O, ═S, or =L′-Y′, whereL′ is selected from the group consisting of N, CH, CF, CCl, and CBr andY′ is selected from the group consisting of H, halogen, N₃, methyl,ethyl, and CN; R is independently halogen, —H, —OH, —SH, —CN,S(C₁-C₄alkyl), —NO₂, NH₂, —NHNH₂, —N₃, —NR′R′ wherein each R′ isindependently H or C₁-C₄ alkyl, —C(S)NH₂, —CH₃, —CH₂OH, —CH₂NH₂, —CH₂NH₃⁺, —COOH, —COOCH₃, —COOCH₂CH₃, —CONHCH₃, —CONH₂, —CF₃, —N(CH₃)₂,—NHCOCH₃, —NHCONH₂, —NHCNHNH₂, —ONH₂, —CH₂OCH₃, —O(CH₂)CH₃,COOC₁-C₄alkyl, optionally substituted alkyl, optionally substitutedalkenyl, optionally substituted alkynyl, optionally substituted aryl,optionally substituted acyl, optionally substituted arylalkyl,optionally substituted cycloalkyl, optionally substituted cycloalkenyl,optionally substituted phenyl, optionally substituted heteroaryl,optionally substituted heterocyclyl, optionally substituted alkyloxy,optionally substituted alkenyloxy, optionally substituted alkynoxy,optionally substituted aryloxy, optionally substituted acyloxy,optionally substituted oxyacyl, optionally substituted arylalkoxy,optionally substituted heterocycloxy, optionally substitutedheteroaryloxy, optionally substituted cycloalkoxy, optionallysubstituted cycloalkenoxy, optionally substituted amino, optionallysubstituted aminoacyl, optionally substituted aminoacyloxy, optionallysubstituted acylamino, optionally substituted oxyacylamino, optionallysubstituted oxyacyloxy, optionally substituted acylimino, optionallysubstituted acyliminoxy, optionally substituted oxyacylimino, optionallysubstituted aminothioacyl, optionally substituted thioacylamino,optionally substituted aminosulfinyl, optionally substitutedaminosulfonyl, optionally substituted thio, optionally substitutedthioalkyl, optionally substituted thioacyl, optionally substitutedthioacyloxy, optionally substituted oxythioacyl, optionally substitutedoxythioacyloxy, optionally substituted phosphorylamino, optionallysubstituted sulfinyl, optionally substituted sulfonyl, optionallysubstituted sulfinylamino, optionally substituted sulfonylamino,optionally substituted oxysulfinylamino, and optionally substitutedoxysulfonylamino; L is selected from the group consisting —O, —S, —NH,—NR, —CY₃, —CY₂O, —CY₂S, —CY₂NH, —CY₂, —CY₂CY₂, —CY₂OCY₂, —CY₂SCY₂, and—CY₂NHCY₂; Y is independently selected from the group consisting of —H,halogen, —R, —OR, and —NR₂; R⁵ is selected from the group consisting of—OH, —R, —OR, —NR₂, or a mono-phosphate, di-phosphate, or tri-phosphatemoiety or mimic thereof; Base is a group of formula II:

wherein the

is a single or double bond; Z¹, Z³, and Z⁴ are independently selectedfrom the group consisting of >C—CONHR, >C—CONR₂,>C—C(S)NH₂, >C—COOR, >C—R, >C—OR, >C—SR, >C—NHR, >C—NR₂, >C-optionallysubstituted heteroaryl, >C-optionally substituted alkyl, and >C-G; Z² isselected from the group consisting of >C—NH₂ and >C═O; G isindependently selected from the group consisting of —H, —F, —Cl, —I,—NH₂, —NHCH₃, —CN, —COOH, —CSNH₂, —CδCH₃, —CδCCH₂OH, —C≡C—Si(CH₃)₃,—CONH₂, —CONHCH₃, —CONH-phenyl, —CONH-methylphenyl, thiazole, oxazole,imidazole, imidazoline, triazole, and tetrazole, and when the compoundcomprises two or more G groups, the G's are identical or different. WhenA is O; R^(1′), R³, R^(4′), and R⁵ are H; L is O; and R^(2′) and R^(3′)are OH; then R² is halogen, OH, NHOH, NHNH₂, N₃, CN, OCOCHNC(CH₃)₂,COOH, CONH₂, C(S)NH₂, COOR, R⁶, OR, SR, SSR, NHR, or NR₂, and R⁶ ishalogen, OH, SH, CN, S(C₁₋₄ alkyl), NO₂, NH₂, NHNH₂, N₃, NR′R′ whereineach R′ is independently H or C₁₋₄ alkyl, C(S)NH₂, CH₃, CH₂OH, CH₂NH₂,CH₂NH₃ ⁺, COOH, COOCH₃, COOCH₂CH₃, CONHCH₃, CONH₂, CF₃, N(CH₃)₂,NHCOCH₃, NHCONH₂, NHCNHNH₂, ONH₂, CH₂OCH₃, O(CH₂)CH₃, COO(C₁₋₄ alkyl),substituted alkyl, substituted alkenyl, substituted alkynyl, substitutedaryl, substituted acyl, substituted arylalkyl, substituted cycloalkyl,substituted cycloalkenyl, substituted phenyl, substituted heteroaryl,substituted heterocyclyl, substituted alkyloxy, substituted alkenyloxy,substituted alkynoxy, substituted aryloxy, substituted acyloxy,substituted oxyacyl, substituted arylalkoxy, substituted heterocycloxy,substituted heteroaryloxy, substituted cycloalkoxy, substitutedcycloalkenoxy, substituted amino, substituted aminoacyl, substitutedaminoacyloxy, substituted acylamino, substituted oxyacylamino,substituted oxyacyloxy, substituted acylimino, substituted acyliminoxy,substituted oxyacylimino, substituted aminothioacyl, substitutedthioacylamino, substituted aminosulfinyl, substituted aminosulfonyl,substituted thio, substituted thioalkyl, substituted thioacyl,substituted thioacyloxy, substituted oxythioacyl, substitutedoxythioacyloxy, substituted phosphorylamino, substituted sulfinyl,substituted sulfonyl, substituted sulfinylamino, substitutedsulfonylamino, substituted oxysulfinylamino, or substitutedoxysulfonylamino; or a pharmaceutically-acceptable salt, ester, solvate,hydrate, or prodrug thereof.

In one embodiment of a compound of formula I, A is oxygen. In anotherembodiment, L is O and R⁵ is H or the mono-, di-, or tri-phosphatemoiety or mimic thereof. In a further embodiment, the plasma half-lifeof the compound is greater than about 2 hours upon administration to ahuman subject. In another embodiment, the compound includes4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazineor one or more pharmaceutically-acceptable salts, esters, solvates,hydrates, or prodrugs thereof. In a further embodiment, a method oftreating a subject in need thereof with the compound of formula I or thecompound that includes4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazineor one or more pharmaceutically-acceptable salts, esters, solvates,hydrates, or prodrugs thereof, includes administering the compound oncedaily to the subject. In another embodiment, the compound that includes4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazineor one or more pharmaceutically-acceptable salts, esters, solvates,hydrates, or prodrugs thereof has a cross-species plasma eliminationhalf-life (t1/2) ranging from 4 to 7.6 hours and an oral bioavailabilityranging from 33 to 96%. In another embodiment, a metabolite is4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine5′-triphosphate and has the structure

In another embodiment, the metabolite has an intracellular half-life of≧38 hours in primary human hepatocytes.

In another aspect, a composition includes the compound of formula I or acompound that includes4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazineor one or more pharmaceutically-acceptable salts, esters, solvates,hydrates, or prodrugs thereof and one or more compounds having anti-HCVactivity.

In a further aspect, a pharmaceutical dosage form includes atherapeutically effective dose of a compound of formula I of thestructure:

wherein R″ is H, F, Cl, I, CN, CONH₂, C≡CSi(C₁₋₄alkyl)₃, COOH, CSNH₂,

R² is C₁₋₄ alkyl, and R⁵ is H,

or a mimic thereof, a salt, ester, solvate, hydrate or prodrug thereof,and one or more pharmaceutical carriers, diluents, or excipients. In oneembodiment, R″ is H, R² is CH₃, and R⁵ is H or

In another embodiment, the pharmaceutical dosage form includes atherapeutically effective dose of an active pharmaceutical ingredient ofthe structure:

or, a salt, ester, solvate, hydrate or prodrug thereof, and one or morepharmaceutical carriers, diluents, or excipients. In a furtherembodiment, the pharmaceutical dosage form is adapted for once dailydosing.

In a further aspect, a pharmaceutical dosage form is provided for use intreating a hepatitis C viral infection by administering to a subject,once per day, said pharmaceutical dosage form comprising atherapeutically effective amount of a compound:

and one or more pharmaceutically acceptable carriers, diluents, orexcipients.

In one embodiment, a therapeutically active dose is in the range ofabout 10 μg/kg to about 30 mg/kg.

In another embodiment, a pharmaceutical dosage form includes ahydrochloride salt of an active pharmaceutical ingredient. In a furtherembodiment, a pharmaceutical dosage form includes an ester of an activepharmaceutical ingredient. In another embodiment, a pharmaceuticaldosage form includes a prodrug of an active pharmaceutical ingredient.In a further embodiment, a pharmaceutical dosage form includes an oral,a rectal, a nasal, a topical, a buccal, a sublingual, a transdermal, avaginal, an injection, or a parental dosage form. In a furtherembodiment, a pharmaceutical dosage form is an oral dosage form.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present disclosure is directed to methods of treatment, kits,combinations, compounds including their use in the manufacture ofmedicaments, and compositions that exhibit antiproliferative effects,for example, via the inhibition of DNA and/or RNA synthesis and thatparticularly may inhibit activity of one or more polymerases, or thattreat a condition where treatment with a polymerase inhibitor, such as aDNA and/or RNA synthesis inhibitor, is indicated. In one embodiment, aDNA and/or RNA synthesis inhibitor includes a bicyclic nucleoside and/ornucleotide, having activity as a polymerase inhibiting agent.

While the present disclosure may be embodied in many different forms,several specific embodiments are discussed herein with the understandingthat the present disclosure is to be considered only as anexemplification of the principles of the invention, and does not limitthe invention to the embodiments illustrated. For example, where theinvention is illustrated herein with particular reference to a compoundhaving inhibitory activity against an HCV NS5B polymerase, it will beunderstood that other polymerases can, if desired, be substituted inwhole or in part for the HCV polymerase herein described.

Although not wishing to be bound by theory, it is believed that amicrobial and/or a proliferative disease or disorder may be treated,attenuated, and/or prevented through manipulation of polymerase activityby using a compound herein described. For example, one microbialpolymerase target, NS5B, an HCV protein, is released from a polyproteinand is involved in the synthesis of double-stranded RNA from asingle-stranded viral RNA genome. It is believed that the replicationand/or reproduction of HCV virus may be inhibited or prevented throughthe inhibition of NS5B and suppress or prevent the formation of thedouble-stranded HCV RNA. Alternatively, it is also believed that anucleoside analogue also may be incorporated into the extending RNAstrand to act as a chain-terminator and/or lead to null mutations.Furthermore, it is believed that a nucleoside analogue or a derivedmetabolite also may be incorporated into the extending RNA, which maycause mutagenic damage to the viral genome.

It is also believed that proliferative disorders including, for example,acute myelogenous leukemia, cholangiocarcinoma, chronic myelogenousleukemia, lymphoma, melanoma, multiple myeloma, osteosarcoma, gastricsarcoma, glioma, bladder, breast, cervical, colorectal, lung, liver,ovarian, pancreatic, prostrate, or stomach cancer, and non-cancerousdiseases associated with excessive and/or inappropriate cell growth,including endothelial cell growth associated with restenosis such ascoronary, carotid, and cerebral lesions, may also be inhibited and/orprevented through the manipulation of polymerase activity by thecompounds described herein, such as D- and/or L-nucleosides andnucleotides of formula I below. Further, decreases in proliferationrates of highly proliferative and/or cancerous cells may be achieved ina manner similar to those described above, namely, thatantiproliferative nucleoside analogues may be incorporated into the RNAand/or replicating genomes of highly proliferative and/or cancerouscells causing, for example, chain-terminator, frame shift, and/or nullmutations that disrupt downstream effector mechanisms required for cellproliferation and metabolic homeostasis.

Such compounds may be screened for antiproliferative and/or polymeraseinhibitory activity by in vitro or in vivo methods known to thoseskilled in the art in addition to the methods set forth herein

Still further, and not wishing to be bound by theory, it is believedthat one or more criteria are desirable for a nucleoside antiviraland/or antiproliferative drug, including, for example, that thenucleoside analogue anabolises to a nucleotide in cells, and/or that theanabolised nucleotide selectively targets viral proteins and/orproliferative mechanisms including, for example, peptide- and/or nucleicacid-based enzymes. It is believed that in order to be phosphorylated incells and selectively target preferred enzymes, nucleoside analogues mayhave favourable modifications on their sugar and base moieties. Toobtain such favourable nucleoside analogues, a general approach is togenerate diverse nucleoside analogues by modifying the base or the sugaror by modifying both base and sugar moieties. Numerous examples exist inthe literature for the synthesis of a variety of modified nucleosides,including, for example, Chemistry of Nucleosides and Nucleotides Vol. 1(1988), Vol. 2 (1991), Vol. 3 (1994), edited by L. B. Townsend, PlenumPress; Handbook of Nucleoside Synthesis by H. Vorbrüggen and C.Ruh-Pohlenz, John Wiley & Sons, Inc., 2001; and The Organic Chemistry ofNucleic Acids by Y. Mizuno, Elsevier, 1986. The resulting modifiedcompounds can then be assayed for desired activity as discussed morefully herein.

While nucleosides incorporating a variety of sugar moieties have beenfound useful for the inhibition of viral polymerases, in the case of theFlaviviridae, and in particular HCV, 2′-C-methyl ribonucleosides havebeen found to be useful (see Eldrup, A. B. et al., J. Med. Chem. 2004,47(21), 5284-97).

The terms “infection” and “microbial infection” (and variations thereof)refers to an infection caused by an infectious agent or microbe, usedherein to include at least bacteria, parasites (including protozoa),viruses, and fungi (including unicellular and multicellular). Examplesof microbes and microbial infections include: Acanthamoeba, Trypanosomabrucei, which causes African sleeping sickness, Entamoeba histolytica,which causes amebiasis, Trypanosoma cruzi, which causes Americantrypanosomiasis or Chagas disease, Schistosoma sp., which causeschistosomiasis or bilharzia, Cryptosporidium parvum, which causescryptosporidiosis, Giardia lamblia, which causes giardiasis, hepatitisA, B, C, D, and E, Leishmania sp., which cause cutaneous and visceralleishmaniasis, Plasmodium falciparum, which causes malaria, Salmonellaenteritides, which causes stomach cramps, diarrhea and fever,Mycobacterium tuberculosis, which causes tuberculosis, Varicella zostervirus, which causes chicken pox, yellow fever virus, pneumonia,Chlamydia and Mycoplasma sp., which cause, for example, urinary tractinfections, meningitis and meningococcal septicemia, Staphylococcusaureus, which causes skin and soft tissue infections, and lowerrespiratory tract infections (bacterial pathogens or viral pathogens).

Additional common infections caused by microbes include, but are notlimited to, those outlined in the following chart:

Infection Bacteria Fungus Protozoa Virus AIDS X Athlete's Foot X ChickenPox X Common Cold X Diarrheal Disease X X X Dengue X Flu X GenitalHerpes X Malaria X X Meningitis X Pneumonia X X Sinusitis X X SkinDisease X X X X Strep Throat X Tuberculosis X Urinary Tract Infections XVaginal Infections X X Viral Hepatitis X

In relation to therapeutic methods of the present disclosure, compoundsof formula I can be useful for inhibiting a polymerase, including, forexample, HCV NS5B polymerase and/or microbial replication, such as HCVreplication and treating a microbial infection, such as HCV infection.Hosts that can be treated may include a unicellular organism, includinga cell line, or a multicellular organism such as an animal, which mayhave one or more host-specific and/or invasive proteins encoded withintheir genomes and functioning in parallel with host proliferativemechanisms or in collaboration with host mechanism in effect to form newvirions, for example, or to alter normal host proliferative patterns.For example, a host includes infected cells, cells transfected with allor part of a genome encoding a polymerase, such as the HCV genome, or ananimal having a proliferative disorder or a microbial infection such asa viral infection caused by an RNA virus, including, for example, avirus belonging to group Flaviviridae, for instance Flaviviruses or HCV,or a DNA or retrovirus such as HBV or HIV.

In one embodiment, a method of the present disclosure treats a viralinfection caused by an RNA virus of the group Flaviviridae and inparticular HCV. An illustrative process for treating a host animalhaving a condition associated with a pathological microbial infection ora proliferative disorder includes administering to the effected host acompound described herein in a therapeutic-effective amount. An exampleof a therapy includes repeated administration of a therapeutic-effectiveamount of one or more compounds to achieve a desired therapeuticoutcome, such as eliminating and/or reducing a viral load in a host to alevel below that prior to the administration of the compound. Anotherexample of a therapy may include repeated administration ofsub-therapeutic-effective amounts that, over time, accumulate to atherapeutic-effective amount. In a further example, a single dose of aneffective amount of one or more compounds and/or salts, esters,solvates, hydrates and prodrugs thereof to achieve a desired therapeuticoutcome is envisioned.

In one embodiment, a compound may be used for treating a host animal,such as a mouse, rat, pig, cow, rabbit, dog, cat, horse, bird, lizard,fish, or primates such as a monkey, chimpanzee, or human that has acondition associated with pathological polymerase activity, such as amicrobial infection and/or a proliferative disorder.

As used herein, the terms “therapeutically effective amount” or“therapeutically effective dose” (and variations thereof) mean an amountof a compound of formula I which, when administered to a host animalaccording to a desired dosing regimen, provides a desired therapeuticactivity for therapeutic treatment and/or prophylactic treatment, suchas, for example, at least partially attaining the desired effect, and/ordelaying the onset of, and/or inhibiting the progression of, and/orpreventing, halting or reversing altogether the onset or progression ofthe particular disease, disorder, and/or condition being treated. Dosingmay be in a single or divided dose and may occur at intervals ofminutes, hours, days, weeks, months, or years or continuously over anyone of these periods, but it is recognized that once daily dosing is adesirable because of the ease of adherence to the regimen by thepatient, especially when the duration of dosing is more than a few days.The half-life of the drug is an important pharmacokinetic parameter indeciding the dosing frequency. The time needed to achieve steady-statedrug concentrations, as well as the time needed to establish newsteady-state concentrations after a change in dosage regimen, is afunction of the elimination half-life of the active therapeutic entity.For once daily dosing a plasma t1/2 of >6 hours is generally required inorder to minimize Cmax/Cmin fluctuations. In the present description, ithas been exemplified that compound 9 has a plasma half-life of 4-7.6hours in preclinical animal species. Furthermore the intracellularhalf-life of the active anabolite of compound 9, compound 25, is 38hours in primary human hepatocytes. The long intracellular half-life ofthe active triphosphate anabolite, coupled with its plasma half-life,generally suggest that compound 9 can be administered, if desired, oncedaily for therapeutic treatment and/or prophylactic treatment of adisease in a patient, including, for example, an infection or microbialinfection such as an infection of liver cells including chronichepatitis C.

Suitable dosages lie within the range of about 0.1 ng per kg of bodyweight to about 10 g per kg of body weight, or in the range of about 1μg to about 10 g per kg of body weight, or in the range of about 10 μgto about 30 mg per kg of body weight, or in the range of about 15 μg toabout 25 mg per kg of body weight, or in the range of about 1 mg toabout 10 g per kg of body weight, or in the range of about 1 mg to about500 mg per kg of body weight, or in the range of about 1 mg to about 250mg per kg of body weight, or in the range of about 1 mg to about 100 mgper kg of body weight per dosage, or up to about 50 mg per body weightper dosage, or greater or less amounts per body weight per dosage.

While not intended to limit the scope of the invention, whenadministered to an animal, such as a human, the composition may beadministered at a dose, for example, a therapeutic-effective amount, toachieve a peak plasma of active molecule of about 0.1 nM to about 100nM, 0.1 μM to about 100 μM, or about 0.5 μM to about 75 μM, or about 1μM to about 50 μM, or greater than or equal to about 0.1 or greater thanor equal to about 0.5 μM or greater than or equal to about 1 μM, and/orintracellular concentration of about 0.1 pmol/million cells to about 100pmol/million cells, 100 pmol/million cells to about 1000 pmol/millioncells, or about 1000 pmol/million cells to about 10000 pmol/millioncells, or greater than or equal to about 10 pmol/million cells, orgreater than or equal to about 50 pmol/million cells or greater than orequal to about 100 pmol/million cells, and may be adjusted over timeaccording to individual need and condition. The peak plasma and/orintracellular concentration of active molecule achieved depends onseveral factors familiar to those skilled in the art including, forexample, route of administration, rates of absorption, protein binding,compound conversion, compound anabolism, compound catabolism,incorporation of a compound into a genome, and excretion andinactivation rates.

Suitable dosage amounts and dosing regimens may be selected inaccordance with a variety of factors, including one or more particularconditions being treated, the severity of the one or more conditions,the genetic profile, age, health, sex, diet, and weight of the subject,the route of administration alone or in combination with pharmacologicalconsiderations including the activity, efficacy, bioavailability,pharmacokinetic, and toxicological profiles of the particular compoundemployed, whether a drug delivery system is utilised and whether thedrug is administered as part of a drug combination. Therefore, thedosage regimen to be employed may vary widely and may necessarilydeviate from the dosage regimens set forth herein.

In one embodiment, an active ingredient of the present disclosure may beadministered in a single dose or a series of doses. While it is possiblefor the active ingredient to be administered alone, for example, as afraction of a formulation scheme and/or a purified compound from a batchreaction, it may be desirable to present it as a composition, such as apharmaceutical composition. Formulation of such compositions is wellknown to those skilled in the art. For example, a candidatepharmaceutical composition may contain one or more carriers, diluents,and/or excipients, and any combination thereof, whereby such carriersare inactive pharmaceutical ingredients. Examples include conventionalsolvents, dispersion media, fillers, solid carriers, coatings,antifungal agents, antibacterial agents, antiviral agents, dermalpenetration agents, surfactants, isotonic agents, absorption agents,adjuvants, analgesics, stabilisers, preservatives, drugs, and the like.It will be understood that the compositions of the invention may alsoinclude other supplementary physiologically active agents. Thesecarriers, diluents and excipients make up a pharmaceutical carriersystem for the compound of formula I.

A candidate carrier that is to be administered to an animal is“pharmaceutically-acceptable” in the sense of being compatible with theother ingredients of the composition and suitably tolerated by the host.Compositions may be adapted according to the desired route ofadministration. For example, compositions herein may be formulated fororal, rectal, nasal, topical (including buccal and sublingual),transdermal, vaginal, injection/injectable, and/or parental (includingsubcutaneous, intramuscular, intravenous, and intradermal)administration. Other suitable administration routes are incorporatedherein. The compositions may be presented conveniently in unit dosageforms and may be prepared by any methods known in the pharmaceuticalarts. Examples of suitable drug formulations and/or forms are discussedin, for example, Hoover, John E. Remington's Pharmaceutical Sciences,Mack Publishing Co., Eston, Pa.; 18^(th) edition (1995); and Liberman,H. A. and Lachman, L. Eds., Pharmaceutical Dosage Forms, Marcel Decker,New York, N.Y., 1980. Illustrative methods include the step of bringingone or more active ingredients into association with a carrier thatconstitutes one or more accessory ingredients. In general, thecompositions may be prepared by bringing into association uniformly andintimately one or more active ingredients with liquid carriers or finelydivided solid carriers or both, and then, if necessary, shaping theproduct.

Compositions suitable for oral administration may be presented asdiscrete units such as capsules, sachets, or tablets each containing apredetermined amount of the active ingredient; as a powder or granules;as a solution or a suspension in an aqueous or non-aqueous liquid; or asan oil-in-water liquid emulsion or a water-in-oil liquid emulsion. Theactive ingredient may also be presented as a bolus, electuary, or paste.

A tablet may be made by compression or moulding, optionally with one ormore accessory ingredients. Compressed tablets may be prepared bycompressing in a suitable machine the active ingredient in afree-flowing form such as a powder or granules, optionally mixed with abinder (for example, inert diluent, preservative disintegrant (forexample, sodium starch glycolate, cross-linked polyvinyl pyrrolidone,cross-linked sodium carboxymethyl cellulose), a surface-active, or adispersing agent). Moulded tablets may be made by moulding in a suitablemachine known to a skilled artisan a mixture of the powdered compoundmoistened with an inert liquid diluent. The tablets may optionally becoated and/or scored and may be formulated so as to provide slow and/orcontrolled release of the active ingredient therein using, for example,hydroxypropylmethyl cellulose in varying proportions to provide one ormore desired release profiles. Tablets may be provided optionally withan enteric coating to provide release in parts of the gut other than thestomach.

Compositions suitable for topical administration in the mouth includelozenges including the active ingredient in a flavoured or unflavouredbase, usually sucrose and acacia or tragacanth gum; pastilles includingthe active ingredient in an inert base, such as gelatine and glycerin,and/or sucrose and acacia gum; and mouthwashes including the activeingredient in a suitable liquid carrier with or without flavouringand/or additional ingredients.

Compositions suitable for topical administration to the skin maycomprise the compounds dissolved or suspended in any suitable carrierand/or base and may be in the form of lotions, gel, creams, pastes,ointments, and the like. Suitable carriers include mineral oil,propylene glycol, polyoxyethylene, polyoxypropylene, emulsifying wax,sorbitan monostearate, polysorbate 60, cetyl esters wax, cetearylalcohol, 2-octyldodecanol, benzyl alcohol, and water. Transdermalpatches may also be used to administer compositions that include one ormore compounds of the invention. Compositions for rectal administrationmay be presented as a suppository with a suitable base including, forexample, cocoa butter, glycerin, gelatine, and/or polyethylene glycol,among others. Compositions suitable for vaginal administration may bepresented as pessaries, tampons, creams, gels, pastes, foams, and/orspray formulations containing compositions containing one or more activeingredient compounds of the present disclosure in addition to one ormore carriers known in the art.

Compositions suitable for parenteral administration include, forexample, aqueous and non-aqueous isotonic sterile injection solutionswhich may contain anti-oxidants, buffers, bactericides, and/or solutesthat render the composition isotonic with the blood of the intendedrecipient; and aqueous and non-aqueous sterile suspensions which mayinclude, for example, suspending agents and thickening agents.Parenteral compositions may be presented in unit-dose or multi-dosesealed containers, for example, ampoules and vials, and may be stored ina freeze-dried (lyophilised) condition requiring only the addition ofthe sterile liquid carrier, for example, water for injections,immediately prior to use. Extemporaneous injection solutions andsuspensions may be prepared from sterile powders, granules and tabletsof the kind described previously. In addition, compositions andformulations may be delivered by a dry powder inhaler in the form of adry powder or delivered by a mist inhaler in the form of a mist.

It should be understood that in addition to the active ingredientsmentioned above, compositions herein may include other agents asappropriate for the type of composition in question. For example,compositions suitable for oral administration may include, for example,binders, colorants, sweeteners, thickeners, flavouring agents,disintegrating agents, coating agents, preservatives, lubricants, and/ortime delay agents. Suitable sweeteners include, for example, sucrose,lactose, glucose, aspartame, and/or saccharine. Suitable disintegratingagents include, for example, cornstarch, methylcellulose,polyvinylpyrrolidone, xanthan gum, bentonite, alginic acid, and/or agar.Suitable flavouring agents include, for example, peppermint oil, oil ofwintergreen, cherry, orange, or raspberry flavouring. Suitable coatingagents include, for example, polymers or copolymers of acrylic acid,and/or methacrylic acid, and/or their esters, waxes, fatty alcohols,zein, shellac, or gluten. Suitable preservatives include, for example,sodium benzoate, vitamin E, alpha-tocopherol, ascorbic acid, methylparaben, propyl paraben, or sodium bisulfite. Suitable lubricantsinclude, for example, magnesium stearate, stearic acid, sodium oleate,sodium chloride, or talc. Suitable time delay agents include, forexample, glyceryl monostearate, or glyceryl distearate.

In addition, other compounds useful in this invention that aresufficiently basic or acidic acids may also form salts. In some cases,the salts can be used as an aid in isolation, purification, resolution,or delivery of the compounds described herein. Further, compounds of thepresent disclosure may be administered in the form of apharmaceutically-acceptable salt. However,non-pharmaceutically-acceptable salts also fall within the scope of thepresent disclosure used, for example, as intermediates in thepreparation of pharmaceutically-acceptable salts or other compounds.

Suitable pharmaceutically-acceptable salts include, but are not limitedto salts of pharmaceutically-acceptable inorganic acids, including, forexample, hydrochloric, sulfuric, phosphoric, nitric, carbonic, boric,sulfamic, and hydrobromic acids, or salts of pharmaceutically-acceptableorganic acids such as acetic, propionic, butyric, tartaric, maleic,hydroxymaleic, fumaric, maleic, citric, lactic, mucic, gluconic,benzoic, succinic, oxalic, phenylacetic, methanesulfonic,toluenesulfonic, benezenesulfonic, salicyclic sulfanilic, aspartic,glutamic, edetic, stearic, palmitic, oleic, lauric, pantothenic, tannic,ascorbic, and valeric acids.

Base salts include, but are not limited to, those formed withpharmaceutically-acceptable cations, including alkali metal and alkalineearth metal salts, such as sodium, potassium, lithium, calcium,magnesium, ammonium, and alkylammonium. In particular, the presentdisclosure includes within its scope cationic salts, for example, sodiumor potassium salts, or alkyl esters (for example, methyl and ethyl) ofthe phosphate group.

Salts of the instant compound may be a pharmaceutically suitable (i.e.,pharmaceutically acceptable) salt including, but not limited to, acidaddition salts formed by mixing a solution of the instant compound witha solution of a pharmaceutically acceptable acid. The pharmaceuticallyacceptable acid may be hydrochloric acid, methanesulphonic acid, fumaricacid, maleic acid, succinic acid, acetic acid, benzoic acid, oxalicacid, citric acid, tartaric acid, carbonic acid or phosphoric acid.Various pharmaceutically acceptable salts are well known in the art andmay be used with the instant compound such as those disclosed in Berge SM et al., “Pharmaceutical Salts.” J. Pharm. Sci. 66:1-19 (1977) andHaynes D A et al., “Occurrence of pharmaceutically acceptable anions andcations in the Cambridge Structural Database,” J. Pharm. Sci.94:2111-2120 (2005), which are hereby incorporated herein by reference.For example, the list of FDA-approved commercially marketed saltsincludes acetate, benzenesulfonate, benzoate, bicarbonate, bitartrate,bromide, calcium edetate, camsylate, carbonate, chloride, citrate,dihydrochloride, edetate, edisylate, estolate, esylate, fumarate,gluceptate, gluconate, glutamate, glycollylarsanilate, hexylresorcinate,hydrabamine, hydrobromide, hydrochloride, hydroxynaphthoate, iodide,isethionate, lactate, lactobionate, malate, maleate, mandelate,mesylate, methylbromide, methylnitrate, methylsulfate, mucate,napsylate, mitrate, pamoate, pantothenate, phosphate, diphosphate,polygalacturonate, salicylate, stearate, subacetate, succinate, sulfate,tannate, tartrate, teoclate, and triethiodide.

In yet another embodiment, the compounds described herein, andderivatives and pharmaceutical compositions thereof, provide for themanufacture of a medicament for the treatment of a microbial infectionand/or a proliferative disease or disorder, including, for example, theinhibition of polymerase activity including RNA-dependent RNA viralreplication, such as HCV replication, and the treatment thereof such asRNA-dependent RNA viral infection.

Numerous variations of and chemical formulation schemes of formula I areincorporated herein. The following definitions and examples are intendedto help describe some potential embodiments.

“Alkyl”, alone or in combination, refers to monovalent alkyl groupswhich may be straight chained or branched and preferably have from 1 to10 carbon atoms or more preferably 1 to 6 carbon atoms. Examples of suchalkyl groups include methyl, ethyl, n-propyl, iso-propyl, n-butyl,iso-butyl, n-hexyl, and the like.

“Alkylene”, alone or in combination, refers to a divalent alkyl groupwherein the alkyl group is as described above.

“Aryl”, alone or in combination, refers to an unsaturated aromaticcarbocyclic group having a single ring (e.g., phenyl) or multiplecondensed rings (e.g., naphthyl or anthryl), preferably having from 6 to14 carbon atoms. Examples of aryl groups include phenyl, naphthyl, andthe like.

“Arylene”, alone or in combination, refers to a divalent aryl groupwherein the aryl group is as described above.

“Aryloxy”, alone or in combination, refers to the group aryl-O— whereinthe aryl group is as described above.

“Arylalkyl”, alone or in combination, refers to -alkylene-aryl groupspreferably having from 1 to 10 carbon atoms in the alkylene moiety andfrom 6 to 10 carbon atoms in the aryl moiety. Such arylalkyl groups areexemplified by benzyl, phenethyl, and the like.

“Arylalkoxy”, alone or in combination, refers to the group arylalkyl-O—,wherein the arylalkyl group is as described above. Such arylalkoxygroups are exemplified by benzyloxy and the like.

“Alkoxy”, alone or in combination, refers to the group alkyl-O— wherethe alkyl group is as described above. Examples include, methoxy,ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert-butoxy, sec-butoxy,n-pentoxy, n-hexoxy, 1,2-dimethylbutoxy, and the like.

“Alkenyl”, alone or in combination, refers to a monovalent alkenyl groupwhich may be straight chained or branched and preferably have from 2 to10 carbon atoms and more preferably 2 to 6 carbon atoms and have atleast 1 and preferably from 1-2, carbon to carbon, double bonds.Examples include ethenyl (—CH═CH₂), n-propenyl (—CH₂CH═CH₂),iso-propenyl (—C(CH₃)═CH₂), but-2-enyl (—CH₂CH═CHCH₃), and the like.

“Alkenyloxy”, alone or in combination, refers to the group alkenyl-O—where the alkenyl group is as described above.

“Alkynyl”, alone or in combination, refers to alkynyl groups preferablyhaving from 2 to 10 carbon atoms and more preferably 2 to 6 carbon atomsand having at least 1, and preferably from 1-2, carbon to carbon, triplebonds. Examples of alkynyl groups include ethynyl (—C≡CH), propargyl(—CH₂C≡CH), pent-2-ynyl (—CH₂C≡CCH₂—CH₃), and the like.

“Alkynyloxy”, alone or in combination, refers to the group alkynyl-O—where the alkynyl group is as described above.

“Acyl”, alone or in combination, refers to groups H—C(O)—, alkyl-C(O)—,cycloalkyl-C(O)—, aryl-C(O)—, heteroaryl-C(O)— and heterocyclyl-C(O)—,where alkyl, cycloalkyl, aryl, heteroaryl, and heterocyclyl are asdescribed herein.

“Oxyacyl”, alone or in combination, refers to groups H—OC(O)—,alkyl-OC(O)—, cycloalkyl-OC(O)—, aryl-OC(O)—, heteroaryl-OC(O)—, andheterocyclyl-OC(O)—, where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Amino”, alone or in combination, refers to the group NR′″″R′″″ whereeach R′″″ is independently hydrogen, alkyl, cycloalkyl, aryl,heteroaryl, and heterocyclyl and where alkyl, cycloalkyl, aryl,heteroaryl, and heterocyclyl are as described herein.

“Aminoacyl”, alone or in combination, refers to the group —C(O)NR′″″R′″″where each R′″ is independently hydrogen, alkyl, cycloalkyl, aryl,heteroaryl, and heterocyclyl and where alkyl, cycloalkyl, aryl,heteroaryl, and heterocyclyl are as described herein.

“Acylamino”, alone or in combination, refers to the group —NR′″″C(O)R′″″where each R′″″ is independently hydrogen, alkyl, cycloalkyl, aryl,heteroaryl, and heterocyclyl, and where alkyl, cycloalkyl, aryl,heteroaryl, and heterocyclyl are as described herein.

“Acyloxy”, alone or in combination, refers to the groups —OC(O)—H,—OC(O)-alkyl, —OC(O)-aryl, —C(O)O-heteroaryl, and —C(O)O-heterocyclylwhere alkyl, aryl, heteroaryl, and heterocyclyl are as described herein.

“Aminoacyloxy”, alone or in combination, refers to the groups—OC(O)NR′″″-H, —OC(O)NR′″″-alkyl, —OC(O)NR′″″-aryl,—OC(O)NR′″″-heteroaryl, and —OC(O)NR′″″-heterocyclyl where R′″″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl, and where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Oxyacylamino”, alone or in combination, refers to the groups—NR′″″C(O)OH, —NR′″″C(O)O-alkyl, —NR′″″C(O)O-aryl,—NR′″″C(O)O-heteroaryl, and NR′″″C(O)O-heterocyclyl where R′″″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl, and where alkyl, cycloalkyl, aryl, heteroaryl andheterocyclyl is as described herein.

“Oxyacyloxy”, alone or in combination, refers to the groups —OC(O)—OH,—OC(O)O-alkyl, —O—C(O)O-aryl, —OC(O)O-heteroaryl, and—OC(O)O-heterocyclyl, and where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Acylimino”, alone or in combination, refers to the groups—C(NR′″″)—R′″″ where each R′″″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl, and where alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl are as described herein.

“Acyliminoxy”, alone or in combination, refers to the groups—O—C(NR′″″)—R′″″ where each R′″″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl, and where alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl are as described herein.

“Oxyacylimino”, alone or in combination, refers to the groups—C(NR′″″)—OR′″″ where each R′″″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl, and where alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl are as described herein.

“Cycloalkyl”, alone or in combination, refers to cyclic alkyl groupshaving a single cyclic ring or multiple condensed rings, preferablyincorporating 3 to 8 carbon atoms. Such cycloalkyl groups include, byway of example, single ring structures such as cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cyclooctyl, and the like, or multiple ringstructures such as adamantanyl, and the like.

“Cycloalkenyl”, alone or in combination, refers to cyclic alkenyl groupshaving a single cyclic ring and at least one point of internalunsaturation, preferably incorporating 4 to 8 carbon atoms. Examples ofsuitable cycloalkenyl groups include, for instance, cyclobut-2-enyl,cyclopent-3-enyl, cyclohex-4-enyl, cyclooct-3-enyl, and the like.

“Halo” or “halogen”, alone or in combination, refers to fluoro, chloro,bromo, and iodo.

“Heteroaryl”, alone or in combination, refers to a monovalent aromaticheterocyclic group which fulfils the Mickel criteria for aromaticity(i.e., contains 4n+2 π electrons, is planar and conjugated) andpreferably has from 2 to 10 carbon atoms and 1 to 4 heteroatoms selectedfrom oxygen, nitrogen, selenium, and sulfur within the ring (andincludes oxides of sulfur, selenium, and nitrogen). Such heteroarylgroups can have a single ring (e.g., pyridyl, pyrrolyl, or N-oxidesthereof, or furyl) or multiple condensed rings (e.g., indolizinyl,benzoimidazolyl, coumarinyl, quinolinyl, isoquinolinyl, orbenzothienyl).

“Heterocyclyl”, alone or in combination, refers to a monovalentsaturated or unsaturated group having a single ring or multiplecondensed rings, preferably from 1 to 8 carbon atoms and from 1 to 4heteroatoms selected from nitrogen, sulfur, oxygen, selenium, andphosphorous within the ring. A more preferred heteroatom is nitrogen.

Examples of heterocyclyl and heteroaryl groups include, but are notlimited to, oxazole, pyrrole, imidazole, imidazoline, pyrazole,pyridine, pyrazine, pyrimidine, pyridazine, indolizine, isoindole,indole, indazole, purine, quinolizine, isoquinoline, quinoline,phthalazine, naphthylpyridine, quinoxaline, quinazoline, cinnoline,pteridine, carbazole, carboline, phenanthridine, acridine,phenanthroline, isothiazole, phenazine, isoxazole, phenoxazine,phenothiazine, imidazolidine, imidazoline, piperidine, piperazine,indoline, phthalimide, 1,2,3,4-tetrahydroisoquinoline,4,5,6,7-tetrahydrobenzo[b]thiophene, thiazole, thiadiazoles, oxadiazole,oxatriazole, tetrazole, thiazolidine, thiophene, benzo[b]thiophene,morpholino, piperidinyl, pyrrolidine, tetrahydrofuranyl, triazole,benzo[1,3]dioxole, and the like. Heterocyclyl rings can optionally alsobe fused to aryl rings, such that the definition includes bicyclicstructures. Typically such fused heterocyclyl groups share one bond withan optionally substituted benzene ring. Examples of benzo-fusedheterocyclyl groups include, but are not limited to, benzo[1,3]dioxole,benzimidazolidinone, tetrahydroquinoline, and methylenedioxybenzene ringstructures. Binding to the heterocycle can be at the position of anheteroatom or via a carbon atom of the heterocycle, or, for benzo-fusedderivatives, via an heteroatom and a carbon atom or of the benzene ring.

“Thio”, alone or in combination, refers to groups H—S—, alkyl-S—,cycloalkyl-S—, aryl-S—, heteroaryl-S—, and heterocyclyl-S—, where alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl are as described herein.

“Thioalkyl”, alone or in combination, refers to —S-alkyl, where alkyl isa described herein.

“Thioacyl”, alone or in combination, refers to groups H—C(S)—,alkyl-C(S)—, cycloalkyl-C(S)—, aryl-C(S)—, heteroaryl-C(S)—, andheterocyclyl-C(S)—, where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Oxythioacyl”, alone or in combination, refers to groups HO—C(S)—,alkylO-C(S)—, cycloalkylO-C(S)—, arylO-C(S)—, heteroarylO-C(S)—, andheterocyclylO-C(S)—, where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Oxythioacyloxy”, alone or in combination, refers to groups HO—C(S)—O—,alkylO—C(S)—O—, cycloalkylO-C(S)—O—, arylO-C(S)—O—, heteroarylO-C(S)—O—,and heterocyclylO-C(S)—O—, where alkyl, cycloalkyl, aryl, heteroaryl,and heterocyclyl are as described herein.

“Phosphorylamino”, alone or in combination, refers to the groups—NR′″″-P(O)(R′″″)(OR″″″) where R′″″ represents H, alkyl, cycloalkyl,alkenyl, or aryl, R″″″ represents OR′″″″ or is hydroxy or amino, andR′″″″ is alkyl, cycloalkyl, aryl, or arylalkyl, where alkyl, amino,alkenyl, aryl, cycloalkyl, and arylalkyl are as described herein.

“Thioacyloxy”, alone or in combination, refers to groups H—C(S)—O—,alkyl-C(S)—O—, cycloalkyl-C(S)—O—, aryl-C(S)—O—, heteroaryl-C(S)—O—, andheterocyclyl-C(S)—O—, where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Sulfinyl”, alone or in combination, refers to groups H—S(O)—,alkyl-S(O)—, cycloalkyl-S(O)—, aryl-S(O)—, heteroaryl-S(O)—, andheterocyclyl-S(O)—, where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Sulfonyl”, alone or in combination, refers to groups H—S(O)₂—,alkyl-S(O)₂—, cycloalkyl-S(O)₂—, aryl-S(O)₂—, heteroaryl-S(O)₂—, andheterocyclyl-S(O)₂—, where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Sulfinylamino”, alone or in combination, refers to groups H—S(O)—NR′″″,alkyl-S(O)—NR′″—, cycloalkyl-S(O)—NR′″″—, aryl-S(O)—NR′″″—,heteroaryl-S(O)—NR′″″—, and heterocyclyl-S(O)—NR′″″—, where R′″″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl, and where alkyl, cycloalkyl, aryl, heteroaryl, andheterocyclyl are as described herein.

“Sulfonylamino”, alone or in combination, refers to groupsH—S(O)₂—NR′″″—, alkyl-S(O)₂—NR′″″—, cycloalkyl-S(O)₂—NR′″″—,aryl-S(O)₂—NR′″″—, heteroaryl-S(O)₂—NR′″″—, andheterocyclyl-S(O)₂—NR′″″—, where R′″″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl, and where alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl are as described herein.

“Oxysulfinylamino”, alone or in combination, refers to groupsHO—S(O)—NR′″″, alkylO-S(O)—NR′″″—, cycloalkylO-S(O)—NR′″″—,arylO-S(O)—NR′″″—, heteroarylO-S(O)—NR′″″—, andheterocyclylO-S(O)—NR′″″—, where R′″″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl, and where alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl are as described herein.

“Oxysulfonylamino”, alone or in combination, refers to groupsHO—S(O)₂—NR′″″, alkylO-S(O)₂—NR′″″—, cycloalkylO-S(O)₂—NR′″″—,arylO-S(O)₂—NR′″″—, heteroarylO-S(O)₂—NR′″″, andheterocyclylO-S(O)₂—NR′″″—, where R′″″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclyl, and where alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl are as described herein.

“Aminothioacyl”, alone or in combination, refers to groupsR′″″R′″″N—C(S)—, where each R′″″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, where alkyl, cycloalkyl, aryl, heteroaryland heterocyclyl are as described herein.

“Thioacylamino”, alone or in combination, refers to groups H—C(S)—NR′″″,alkyl-C(S)—NR′″″—, cycloalkyl-C(S)—NR′″″—, aryl-C(S)—NR′″″—,heteroaryl-C(S)—NR′″″—, and heterocyclyl-C(S)—NR′″″—, where R′″″ isindependently hydrogen, alkyl, cycloalkyl, aryl, heteroaryl, and wherealkyl, cycloalkyl, aryl, heteroaryl and heterocyclyl are as describedherein.

“Aminosulfinyl”, alone or in combination, refers to groupsR′″″R′″″N—S(O)—, where each R′″″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclic, and where alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl are as described herein.

“Aminosulfonyl”, alone or in combination, refers to groupsR′″″R′″″N—S(O)₂—, where each R′″″ is independently hydrogen, alkyl,cycloalkyl, aryl, heteroaryl, and heterocyclic, and where alkyl,cycloalkyl, aryl, heteroaryl and heterocyclyl are as described herein.

The term “substituted” (and variations thereof) means that a issubstituted or fused (for example, so as to form a condensed polycyclicgroup) with one or more groups such as hydroxyl, acyl, alkyl, alkoxy,alkenyl, alkenyloxy, alkynyl, alkynyloxy, amino, aminoacyl, thio,arylalkyl, arylalkoxy, aryl, aryloxy, acylamino, cyano, halogen, nitro,sulfo, phosphono, phosphorylamino, phosphinyl, heteroaryl,heteroaryloxy, heterocyclyl, heterocycloxy, oxyacyl, acyloxy, oxime,oxime ether, hydrazone, oxyacylamino, aminoacyloxy, trihalomethyl,trialkylsilyl, pentafluoroethyl, trifluoromethoxy, difluoromethoxy,trifluoromethanethio, trifluoroethenyl, mono- or di-alkylamino, mono- ordi-(substituted alkyl)amino, mono- or di-arylamino, mono- ordi-heteroarylamino, mono- or di-heterocyclyl amino, unsymmetricdi-substituted amines having different substituents selected from alkyl,aryl, heteroaryl, or heterocyclyl, and other like substitutions. Theterm “substituted amino” group includes amino acid and peptide residues.“Substituted phenyl” group includes, for example, 1,3-benzodioxole,4-methoxyphenyl, 4-azacyclohexyl, 2-aminophenyl, 4-fluorophenyl,2-fluorocphenyl, 3-acetylphenyl, and methylbenzyl.

The term “base”, unless otherwise specified, refers to the base moietyof a nucleoside or nucleotide. The base moiety is thenitrogen-heterocycle portion of a nucleoside or nucleotide. The basemoiety of a nucleotide of formula I is a heterocycle represented byformula (II) and designated “Base.” The nucleoside base is attached tothe sugar moiety of a nucleoside in such ways that both α and β anomersof D or L nucleosides can be produced. This is denoted by use of the

bond, which links the base to the sugar moiety.

The term “sugar” refers to the furanose portion of a nucleoside ornucleotide. The sugar moiety of formula I nucleosides, nucleotides, andnucleotides mimics and/or prodrugs thereof may contain one or moresubstituents at their C1-, C2-, C3- and C4-positions of the furanose.Substituents may be directed to either the α- or β-face of the furanose.The nucleoside or nucleotide base can be considered as a substituent atthe C-1 position of the furanose and is preferably directed to theβ-face of the sugar. The β-face is the side of a furanose on which apurine or pyrimidine base of natural β-D-nucleosides, for example, ispresent. The α-face is the side of the sugar opposite to the β-face.

The terms “protecting group” (and variations thereof) refer to a moietyor substituent that alters or masks a property or reactivity of anothermoiety, such as, for example, altering the polarity, lipophilicity orhydrophobicity of a functional group. Examples of protecting groups andthe chemical structure are extensive and vary widely. Examples of a“protecting group” for O, S, N, hydroxyl or NH₂, include moieties suchas acyl groups, silyl groups, and the like. A protecting group may alsoserve as an intermediate in the synthesis of a desired compound toassist, for example, in the efficiency of a desired reaction byfacilitating the making and/or breaking of chemical bonds in a syntheticpathway. A protecting group may also improve or enhance drug absorption,solubility, lipophilicity, bioavailability, efficacy, and/or drugdelivery into cells and may also be referred to as a prodrug. In such acase, the protecting group converts a therapeutically-active compoundinto a prodrug as described herein. In any event, a compound containinga protecting group may be biologically active or inactive. Othersuitable protecting groups for these and other moieties are described byT. W. Greene and P. G. M. Wuts; Protecting Groups in Organic Synthesis,3^(rd) Ed, John Wiley & Sons, Inc. (1999).

As used herein, “hydrates” of the instant compound may be apharmaceutically suitable (i.e., pharmaceutically acceptable) hydratethat is a compound formed by the addition of water or its elements to ahost molecule (e.g., the free form version of the compound) including,but not limited to, monohydrates, dihydrates, etc.

As used herein, “solvates” of the instant compound may be apharmaceutically suitable (i.e., pharmaceutically acceptable) solvate,whereby solvation is an interaction of a solute with the solvent whichleads to stabilization of the solute species in the solution, andwhereby the solvated state is an ion in a solution complexed by solventmolecules. Solvates and hydrates may also be referred to as “analogues.”

The present disclosure relates to, in particular, nucleoside andnucleotide analogue compounds that may function as antiproliferativeagents, for example, via polymerase inhibition, and more particularly tobicyclic nucleosides and nucleotides for the treatment of diseases suchas proliferative and infectious diseases, compositions of thosecompounds, intermediates for the synthesis of those compounds, processesfor the preparation of those compounds, and processes for treating acondition associated with the disease.

A compound of formula I corresponds in structure to formula I:

wherein the

defines the active pharmaceutical ingredient as a D- or L-nucleoside ornucleotide; A is selected from the group consisting of —O—, —S—, —CH₂—,—CHF—, —CF₂—, and —NR—; R^(1″), R², R^(2′), R³, R^(3′), and R^(4′) areindependently selected from the group consisting of —H, halogen, —OH,—NHOH, —NHNH₂, —N₃, —CN, —OCOCHNC(CH₃)₂, —COOH, —CONH₂, —C(S)NH₂, —COOR,—R, —OR, —SR, —SSR, —NHR, and —NR₂, or R² and R^(2′) together or R³ andR^(3′) together represents ═O, ═S, or =L′-Y′, where L′ is selected fromthe group consisting of N, CH, CF, CCl, and CBr and Y′ is selected fromthe group consisting of H, halogen, N₃, methyl, ethyl, and CN; R isindependently halogen, —H, —OH, —SH, —CN, S(C₁-C₄alkyl), —NO₂, NH₂,—NHNH₂, —N₃, —NR′R′ wherein each R′ is independently H or C₁-C₄ alkyl,—C(S)NH₂, —CH₃, —CH₂OH, —CH₂NH₂, —CH₂NH₃ ⁺, —COOH, —COOCH₃, —COOCH₂CH₃,—CONHCH₃, —CONH₂, —CF₃, —N(CH₃)₂, —NHCOCH₃, —NHCONH₂, —NHCNHNH₂, —ONH₂,—CH₂OCH₃, —O(CH₂)CH₃, COOC₁-C₄alkyl, optionally substituted alkyl,optionally substituted alkenyl, optionally substituted alkynyl,optionally substituted aryl, optionally substituted acyl, optionallysubstituted arylalkyl, optionally substituted cycloalkyl, optionallysubstituted cycloalkenyl, optionally substituted phenyl, optionallysubstituted heteroaryl, optionally substituted heterocyclyl, optionallysubstituted alkyloxy, optionally substituted alkenyloxy, optionallysubstituted alkynoxy, optionally substituted aryloxy, optionallysubstituted acyloxy, optionally substituted oxyacyl, optionallysubstituted arylalkoxy, optionally substituted heterocycloxy, optionallysubstituted heteroaryloxy, optionally substituted cycloalkoxy,optionally substituted cycloalkenoxy, optionally substituted amino,optionally substituted aminoacyl, optionally substituted aminoacyloxy,optionally substituted acylamino, optionally substituted oxyacylamino,optionally substituted oxyacyloxy, optionally substituted acylimino,optionally substituted acyliminoxy, optionally substituted oxyacylimino,optionally substituted aminothioacyl, optionally substitutedthioacylamino, optionally substituted aminosulfinyl, optionallysubstituted aminosulfonyl, optionally substituted thio, optionallysubstituted thioalkyl, optionally substituted thioacyl, optionallysubstituted thioacyloxy, optionally substituted oxythioacyl, optionallysubstituted oxythioacyloxy, optionally substituted phosphorylamino,optionally substituted sulfinyl, optionally substituted sulfonyl,optionally substituted sulfinylamino, optionally substitutedsulfonylamino, optionally substituted oxysulfinylamino, and optionallysubstituted oxysulfonylamino; L is selected from the group consisting—O, —S, —NH, —NR, —CY₃, —CY₂O, —CY₂S, —CY₂NH, —CY₂, —CY₂CY₂, —CY₂OCY₂,—CY₂SCY₂, and —CY₂NHCY₂; Y is independently selected from the groupconsisting of —H, halogen, —R, —OR, and —NR₂; R⁵ is selected from thegroup consisting of —OH, —R, —OR, —NR₂, or a mono-phosphate,di-phosphate, or tri-phosphate moiety or mimic thereof; Base is a groupof formula II:

wherein the dashed line “

” is a single or double bond; Z¹, Z³, and Z⁴ are independently selectedfrom the group consisting of >C—CONHR, >C—CONR₂,>C—C(S)NH₂, >C—COOR, >C—R, >C—OR, >C—SR, >C—NHR, >C—NR₂, >C-optionallysubstituted heteroaryl, >C-optionally substituted alkyl, and >C-G; Z² isselected from the group consisting of >C—NH₂ and >C═O; G isindependently selected from the group consisting of —H, —F, —Cl, —I,—NH₂, —NHCH₃, —CN, —COOH, —CSNH₂, —CδCH, —CδCCH₃, —CδCCH₂OH,—CδC—Si(CH₃)₃, —CONH₂, —CONHCH₃, —CONH-phenyl, —CONH-methylphenyl,thiazole, oxazole, imidazole, imidazoline, triazole, and tetrazole, or apharmaceutically-acceptable salt, ester, solvate, hydrate, or prodrugthereof.

In one exemplary embodiment, when a compound of formula I comprises twoor more G groups, the G's are identical or different.

In another exemplary embodiment, when A is O; R^(1′), R³, R^(4′), and R⁵are H; L is O; and R^(2′) and R^(3′) are OH; then R² is halogen, OH,NHOH, NHNH₂, N₃, CN, OCOCHNC(CH₃)₂, COOH, CONH₂, C(S)NH₂, COOR, R⁶, OR,SR, SSR, NHR, or NR₂, and R⁶ is halogen, OH, SH, CN, S(C₁₋₄ alkyl), NO₂,NH₂, NHNH₂, N₃, NR′R′ wherein each R′ is independently H or C₁₋₄ alkyl,C(S)NH₂, CH₃, CH₂OH, CH₂NH₂, CH₂NH₃ ⁺, COOH, COOCH₃, COOCH₂CH₃, CONHCH₃,CONH₂, CF₃, N(CH₃)₂, NHCOCH₃, NHCONH₂, NHCNHNH₂, ONH₂, CH₂OCH₃,O(CH₂)CH₃, COO(C₁₋₄ alkyl), substituted alkyl, substituted alkenyl,substituted alkynyl, substituted aryl, substituted acyl, substitutedarylalkyl, substituted cycloalkyl, substituted cycloalkenyl, substitutedphenyl, substituted heteroaryl, substituted heterocyclyl, substitutedalkyloxy, substituted alkenyloxy, substituted alkynoxy, substitutedaryloxy, substituted acyloxy, substituted oxyacyl, substitutedarylalkoxy, substituted heterocycloxy, substituted heteroaryloxy,substituted cycloalkoxy, substituted cycloalkenoxy, substituted amino,substituted aminoacyl, substituted aminoacyloxy, substituted acylamino,substituted oxyacylamino, substituted oxyacyloxy, substituted acylimino,substituted acyliminoxy, substituted oxyacylimino, substitutedaminothioacyl, substituted thioacylamino, substituted aminosulfinyl,substituted aminosulfonyl, substituted thio, substituted thioalkyl,substituted thioacyl, substituted thioacyloxy, substituted oxythioacyl,substituted oxythioacyloxy, substituted phosphorylamino, substitutedsulfinyl, substituted sulfonyl, substituted sulfinylamino, substitutedsulfonylamino, substituted oxysulfinylamino, or, substitutedoxysulfonylamino.

In one embodiment of a compound of formula I,

is a double bond, Z¹ is >C—R″, Z² is >C—NH₂, Z³ is >C—R′″, Z⁴ is >C—R′″,and R″, R′″ and R″″ are each independently H, F, I, Cl, NH₂, NHCH₃,C(═O)NH₂, C(═O)NHCH₃, C(═O)NH(C₆H₅), C(═O)NH(C₆H₅CH₂), CN, C≡CH, C≡CCH₃,C≡CCH₂OH, C≡C—Si(CH₃)₃, C(═S)NH₂, CO₂H,

In another embodiment of a compound of formula I,

is a single bond, Z¹ is >C—R″, Z² is >C═O, Z³ is >C—R′″, Z⁴ is >C—R″″,and R″, R′″ and R″″ are each independently H, F, I, Cl, NH₂, NHCH₃,CO)NH₂, C(═O)NHCH₃, C(═O)NH(C₆H₅), —C(═O)NH(CH₂C₆H₅), CN, C≡CCH₃,C≡CCH₂OH, C≡C—Si(CH₃)₃, C(═S)NH₂, CO₂H,

In yet another embodiment of a compound of formula I, Z⁴ is >C—H.

In still another embodiment of a compound of formula I, Z⁴ is >C—R″″,and R″″ is F, I, Cl, NH₂, NHCH₃, C(═O)NH₂, C(═O)NHCH₃, C(═O)NHC₆H₅,C(═O)NH(CH₂C₆H₅), CN, C≡CH, C≡CCH₂OH, C≡C—Si(CH₃)₃, C(═S)NH₂, CO₂H,

In another embodiment of a compound of formula I, Z⁴ is >C—R″″ and R″″is F, I or Cl.

In another embodiment of a compound of formula I, Z³ is >C—R′″, and R′″is H.

In another embodiment of a compound of formula I, Z³ is >C—R′″, and R′″is NH₂.

In another embodiment of a compound of formula I, Z¹ is >C—H.

In another embodiment of a compound of formula I, Z¹ is >C—R″, and R″ isindependently F, I, Cl, NH₂, NHCH₃, C(═O)NH₂, C(═O)NHCH₃, C(═O)NHC₆H₅,C(═O)NHCH₂C₆H₅, CN, C≡CH, C≡CCH₃, C≡CH₂OH, C═C—Si(CH₃)₃, C(═S)NH₂, CO₂H,

In another embodiment of a compound of formula I, A is oxygen.

In another embodiment of a compound of formula I, L is O, and R⁵ is H orthe mono-, di- or tri-phosphate moiety or mimic thereof.

In another embodiment, a compound of formula I is selected from4-amino-5-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;4-amino-5-chloro-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;4-Amino-5-iodo-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine-5-carbonitrile;4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine-5-carboxylicacid amide;4-amino-5-trimethylsilanylethynyl-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;4-amino-5-ethynyl-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine-5-carboxylicacid;2,4-diamino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine-5-carbothioicacid amide;4-amino-5-oxazol-2-yl-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;4-amino-5-thiazol-2-yl-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;4-amino-5-(3H-[1,2,3]triazol-4-yl)-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;4-Amino-6-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazin-7-yl;4-amino-5-imidazole-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine;and4-amino-5-imidazoline-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine.

In another embodiment, a compound of formula I is4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine.

In another embodiment of a compound of formula I, R⁵ is aphosphoramidate or a phosphoester of the mono-, di- or tri-phosphatemoiety.

In yet another embodiment, Se may be substituted for S independently atevery position where S is an option. A compound of the presentdisclosure also includes a pharmaceutically-acceptable salt, ester,solvate, hydrate and/or a prodrug thereof.

In one embodiment, the sugar moiety may be represented by the following:

and C-5 mono-phosphate, di-phosphate, and tri-phosphate derivativesthereof, or C-5 mono-phosphate, di-phosphate, and tri-phosphate mimicderivatives thereof, and prodrug moieties thereof such as phosphoestersand phosphoamidates.

In a further embodiment, the sugar moiety may be represented by thefollowing formulae:

and C-5 mono-phosphate, di-phosphate, and tri-phosphate derivativesthereof, or C-5 mono-phosphate, di-phosphate, and tri-phosphate mimicderivatives thereof.

In yet a further embodiment, the sugar moiety may be represented by thefollowing formulae:

and C-5 mono-phosphate, di-phosphate, and tri-phosphate derivativesthereof, or C-5 mono-phosphate, di-phosphate, and tri-phosphate mimicderivatives thereof.

In a further embodiment, the sugar moiety may be represented by thefollowing formulae:

and C-5 mono-phosphate, di-phosphate, and tri-phosphate derivativesthereof, or C-5 mono-phosphate, di-phosphate, and tri-phosphate mimicderivatives thereof.

In yet a further embodiment, the sugar moiety may be represented by thefollowing formulae:

and C-5 mono-phosphate, di-phosphate, and tri-phosphate derivativesthereof, or C-5 mono-phosphate, di-phosphate, and tri-phosphate mimicderivatives thereof.

Accordingly, one embodiment of the compound of formula I may berepresented by the following formulae, or salts, esters, solvates,hydrates or prodrugs thereof:

Furthermore, another embodiment of the compound of formula I may berepresented by the following formulae, or salts, esters, solvates,hydrates or prodrugs thereof:

Each R may be halogen, —H, —OH, —SH, —CN, S(C₁-C₄ alkyl), —NO₂, NH₂,—NHNH₂ or —N₃, —NR′R′. Each R′ may independently be H, C₁-C₄ alkyl,—C(S)NH₂, —CH₃, —CH₂OH, —CH₂NH₂, —CH₂NH₃ ⁺, —COOH, —COOCH₃, —COOCH₂CH₃,—CONHCH₃, —CONH₂, —CF₃, —N(CH₃)₂, —NHCOCH₃, —NHCONH₂, —NHCNHNH₂, —ONH₂,—CH₂OCH₃, —O(CH₂)CH₃, COO(C₁-C₄alkyl), substituted alkyl, substitutedalkenyl, substituted alkynyl, substituted aryl, substituted acyl,substituted arylalkyl, substituted cycloalkyl, substituted cycloalkenyl,substituted phenyl, substituted heteroaryl, substituted heterocyclyl,substituted alkyloxy, substituted alkenyloxy, substituted alkynoxy,substituted aryloxy, substituted acyloxy, substituted oxyacyl,substituted arylalkoxy, substituted heterocycloxy, substitutedheteroaryloxy, substituted cycloalkoxy, substituted cycloalkenoxy,substituted amino, substituted aminoacyl, substituted aminoacyloxy,substituted acylamino, substituted oxyacylamino, substituted oxyacyloxy,substituted acylimino, substituted acyliminoxy, substitutedoxyacylimino, substituted aminothioacyl, substituted thioacylamino,substituted aminosulfinyl, substituted aminosulfonyl, substituted thio,substituted thioalkyl, substituted thioacyl, substituted thioacyloxy,substituted oxythioacyl, substituted oxythioacyloxy, substitutedphosphorylamino, substituted sulfinyl, substituted sulfonyl, substitutedsulfinylamino, substituted sulfonylamino, substituted oxysulfinylaminoor substituted oxysulfonylamino. Each G may be —H, —F, —Cl, —I, —NH₂,—NHCH₃, —CN, —C≡CH, —C≡CCH₃, —C≡CCH₂OH, —C≡C—Si(CH₃)₃, —CONH₂, —CSNH₂,—COON, —CONHCH₃, —CONH-phenyl, —CONH-methylphenyl, thiazole, oxazole,imidazole, imidazoline, triazole or tetrazole. The C-5 mono-phosphate,di-phosphate, and tri-phosphate derivatives thereof, or C-5mono-phosphate, di-phosphate, and tri-phosphate mimic derivativesthereof.

In another embodiment, the sugar moiety may be represented by any one ofthe following structures:

or C-5 mono-phosphate, di-phosphate and tri-phosphate derivativesthereof, or C-5 mono, di or tri-phosphate mimics. The nucleosides of thepresent disclosure also include derivatives such as nucleotides, andnucleotide mimics and/or prodrugs thereof such as phosphoesters andphosphoamidates.

In various embodiments, nucleotide mimics of the compounds of thepresent disclosure of formula I discussed above include a compound inwhich R⁵ is a mono-phosphate or mono-phosphate mimic of formula (III) or(IV):

The X^(1′)X^(4′), and X^(6′) moieties are independently ═O, ═S or ═NR.The X^(2′), X^(3′), and X^(5′) moieties may be —H, —F, —NROR, —N₃, —CN,—(BH₂G)⁻M⁺, —(BH₃)⁻M⁺, —R, —OR, —SR or —NR₂. The substituents(BH₂G)⁻M⁺and (BH₃)⁻M⁺are ion pairs, which are linked to phosphorusthrough the negatively charged boron. M⁺is a cation, such as apharmaceutically-acceptable cation like Ca²⁺, ammonium, trialkylammoniumor tetraalkylammonium, e.g., NH₄ ⁺, Et₃NH⁺, Bu₃NH⁺, and Bu₄N⁺.

In various embodiments, nucleotide mimics of the compounds of formula Ias discussed above include di- and tri-phosphates and di- andtri-phosphate mimics including a compound in which R⁵ is a di- ortri-phosphate moiety of formula (V):

The X², X³, and X⁴ may be ═O, ═S, ═Se or ═NR. The X⁵ and X⁶ may be —O—,—S—, —Se—, —CY₂C(O)—, —CH(OH)—, —C(OH)₂—, —CH₂O—, —CH₂CH₂—,—CH₂CH(NH₂)—, —CH₂CH₂CH(NH₂)—, —CY₂OCY₂—, —CY₂—, —CRY—, —CY₂CY₂—, —CHR—,—C≡C—, —HC═CH—, —NH—, —NR—, >NOH, >NOR, >NNH₂ or >NNHR. The X⁷, X⁸, X⁹and X¹⁰ may be —H, —F, —OR, —SR, —NR₂, —NROR, —NRNR₂, —CN, —N₃,—(BH₃)⁻M⁺, —(BH₂G)⁻M⁺, —R and —SeR; —Y, —R, wherein —(BH₂G)⁻M⁺, and—(BH₃)⁻M⁺are as defined above. The n is 0 or 1.

The terms “phosphate mimic” (and variations thereof) unless otherwisespecified, refers to a phosphate analogue, including, but not limitedto, phosphonate, phosphothiolate, phosphoselenoate, selenophosphate,thiophosphate, P-boranophosphate, phosphoramidate, sulfamate, sulfonate,sulfonamide, and/or a combination thereof. Illustrative embodiments ofthe phosphate mimics include phosphonate, phosphoramidate,phosphorothioate, methylphosphonate, fluoromethylphosphonate,difluoromethylphosphonate, vinylphosphonate, phenylphosphonate,sulfonate, fluorophosphate, dithiophosphorothioate,5′-methylenephosphonate, 5′-difluoromethylenephosphonate,5′-deoxyphosphonate, 5′-aminophosphoramidate, and 5′-thiophosphate.

Also, it will be appreciated that the terms “di-phosphate mimic” and“tri-phosphate mimic” specifically refer to a di-phosphate analogue anda tri-phosphate analogue, respectively, which include at least one ofthe phosphate mimics, one of the modifications at the bridging site ofdi-phosphate and tri-phosphate (e.g., X⁵, X⁶ and X¹⁰), and/orreplacements of non-bridging phosphate oxygen atoms (e.g., X⁴, X³ andX²).

Additional nucleotide phosphate mimics and methods of making appropriatephosphate mimics for compounds of the present disclosure are described,inter alia, in WO 2003/072757 and WO 2003/073989, the entire contents ofwhich are incorporated herein by reference. Many of the nucleotidemimics discussed herein may be prepared by similar approaches aspublished or by using well-known knowledge of organophosphorouschemistry. Generally, phosphate mimics of the nucleosides andnucleotides of the present disclosure may inhibit enzyme functionwithout phosphorylation and/or have enhanced nuclease stability relativeto nucleotides with unmodified phosphate.

The α-P, β-P, and γ-P in the mono-phosphate, di-phosphate, andtri-phosphate mimics may independently adopt either R or Sconfigurations when chiral.

In yet another embodiment of the present disclosure, a pharmaceuticaldosage form comprises a compound of formula I and one or morepharmaceutically acceptable carriers, diluents and/or excipients.

In another embodiment of a pharmaceutical dosage form, a therapeuticallyeffective dose of a compound of formula I is provided for a microbialinfection, a viral infection, or a proliferative disorder in a humanpatient in the range of about 10 μg/kg to about 30 mg/kg.

In another embodiment, a pharmaceutical dosage form comprises sufficientcompound of a compound of formula Ito provide once a day dosing to ahuman patient.

Another aspect of the invention is a method of treating or preventing amicrobial infection, a viral infection, or a proliferative disorder in ahuman patient comprising administering a pharmaceutical dosage form of acompound of formula Ito the human patient.

In an exemplary embodiment of the methods, the condition is a viralinfection.

In an exemplary embodiment of the methods, the viral infection is aFlaviviridae infection, preferably a hepatitis C viral infection.

In yet another embodiment, the method is directed to treating thehepatitis C viral infection in a human patient comprising administeringto the human patient a pharmaceutical dosage form comprising atherapeutically effective amount of4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazineand one or more pharmaceutically acceptable carriers, diluents and/orexcipients.

In another embodiment of the present disclosure, a therapeuticallyeffective amount is between about 10 μg/kg to about 30 mg/kg.

In yet another aspect of the present disclosure, a method of inhibitingpolymerase activity in a human patient comprises administering apharmaceutical dosage form to the human patient.

In an exemplary embodiment of the methods, the polymerase activity isHCV NS5B polymerase activity.

In another exemplary embodiment of the methods, a pharmaceutical dosageform is administered once a day.

In still another exemplary embodiment of the methods, a therapeuticallyactive compound of the compound of formula I is Z¹ is H, R² is CH₃, andR⁵ is H or

In yet another exemplary embodiment, a therapeutically active compoundof a compound of formula I comprises a phosphoramidate or a phosphoesterof R⁵.

In yet another exemplary embodiment, a therapeutically active compoundof a compound of formula I comprises a hydrochloride salt of thetherapeutically active compound.

In another embodiment, a method is provided directed to treating ahepatitis C viral infection by administering to a patient, once per day,a pharmaceutical dosage form comprising a therapeutically effectiveamount of a compound:

and one or more pharmaceutically acceptable carriers, diluents and/orexcipients.

In yet another embodiment, a method is provided directed toadministering to a patient a therapeutically effective amount of acompound of formula I in the range of about 10 μg/kg to about 30 mg/kg.

In another exemplary embodiment, the method comprises the in-vivoproduction of a therapeutically effective metabolite of a compound offormula I that has an intracellular half-life of greater than about 10hours.

In another exemplary embodiment, the method comprises the in-vivoproduction of a therapeutically effective metabolite to allow for once aday dosing of formula I in a human patient in the range of about 10μg/kg to about 30 mg/kg.

In another exemplary embodiment, the plasma half-life of a compound offormula I is greater than about 2 hours upon administration to a humanpatient.

In another exemplary embodiment, a pharmaceutical dosage form at anextracellular concentration of 10 μM of a compound of formula I resultsin intracellular levels of a therapeutically active compound thereof inprimary cells of greater than about 20 pmoles/million cells.

In another exemplary embodiment, a pharmaceutical dosage form comprisesa therapeutically effective dose of a compound of formula I according tothe structure:

wherein:

R″ is H, F, Cl, I, CN, CONH₂, C≡CSi(C₁₋₄ alkyl)₃, CCH, COOH, CSNH₂,

R² is C₁₋₄ alkyl, and

R⁵ is H,

or mimic thereof, or, a salt, ester, solvate, hydrate or prodrugthereof, and one or more pharmaceutical carriers, diluents and/orexcipients.

In another exemplary embodiment, a pharmaceutical dosage form comprisesa compound of formula I as depicted above wherein R″ is H, R² is CH₃,and R⁵ is H or

In another exemplary embodiment, a pharmaceutical dosage form comprisesa phosphoramidate or a phosphoester of R⁵.

In another exemplary embodiment, a pharmaceutical dosage form comprisesa therapeutically effective dose of an active pharmaceutical ingredientaccording to the structure:

or, a salt, ester, solvate, hydrate or prodrug thereof, and one or morepharmaceutical carriers, diluents and/or excipients.

In yet another exemplary embodiment, a pharmaceutical dosage formcomprises a therapeutically effective dose of an active pharmaceuticalingredient in the range of 10 μz/kg to 30 mg/kg.

In yet another exemplary embodiment, a pharmaceutical dosage formcomprises a hydrochloride salt of an active pharmaceutical ingredient.

In another exemplary embodiment, a pharmaceutical dosage form comprisesan ester of an active pharmaceutical ingredient.

In another exemplary embodiment, a pharmaceutical dosage form comprisesa prodrug of an active pharmaceutical ingredient.

In another exemplary embodiment, the pharmaceutical dosage form is anoral, a rectal, a nasal, a topical, a buccal, a sublingual, atransdermal, a vaginal, an injection or a parental dosage form.

Compounds of the present disclosure can possess one or more asymmetriccarbon atoms and are thus capable of existing in the form of opticalisomers as well as in the form of racemic or non-racemic mixturesthereof. The optical isomers can be obtained by resolution of theracemic mixtures according to conventional processes well known in theart, for example, by formation of diastereoisomeric salts by treatmentwith an optically active acid or base. Examples of appropriate acids aretartaric, diacetyltartaric, dibenzoyltartaric, ditoluoyltartaric andcamphorsulfonic acid and then separation of the mixture ofdiastereoisomers by crystallization followed by liberation of theoptically active bases from these salts. A different process forseparation of optical isomers involves the use of a chiralchromatography column optimally chosen to maximise the separation of theenantiomers.

Still another available method involves synthesis of covalentdiastereomeric molecules, for example, esters, amides, acetals, ketals,and the like, by reacting compounds of formula I with an opticallyactive acid in an activated form, an optically active diol, or anoptically active isocyanate. The synthesised diastereoisomers can beseparated by conventional means such as chromatography, distillation,crystallization or sublimation, and then hydrolyzed to deliver theenantiomerically pure compound. In some cases, hydrolysis to the parentoptically active drug is not necessary prior to dosing the patient sincethe compound can behave as a prodrug. The optically active compounds offormula I can likewise be obtained by utilizing optically activestarting materials.

In addition to the optical isomers or potential optical isomersdiscussed above, other types of isomers are specifically intended to beincluded in this disclosure. Examples include cis isomers, transisomers, E isomers, Z isomers, syn-isomers, anti-isomers, tautomers andthe like. Aryl, heterocyclyl, or heteroaryl tautomers, heteroatomisomers and ortho, meta, or para substitution isomers are also includedas isomers. Solvates or solvent addition compounds such as hydrates oralcoholates are also specifically included both as chemicals of thisdisclosure and in, for example, formulations or pharmaceuticalcompositions for delivery.

Equivalents of the general formulas set forth above for the disclosedcompounds and derivatives as well as the intermediates are compoundsotherwise corresponding thereto and having the same general propertiessuch as tautomers thereof and compounds wherein one or more of thevarious R groups are simple variations of the substituents as definedtherein, for example, wherein R is a higher alkyl group than thatindicated. In addition, where a substituent is designated as, or can be,hydrogen, the exact chemical nature of a substituent which is other thanhydrogen at that position, for example, a halogen, hydroxy, amino, andthe like functional group, is not critical so long as it does notadversely affect the overall activity and/or synthesis procedure. Forexample, two hydroxyl groups, two amino groups, two thiol groups or amixture of two hydrogen-heteroatom groups on the same carbon are knownnot to be stable without protection or as a derivative.

Basic nitrogen-containing groups may be quarternised with such agents aslower alkyl halide, such as methyl, ethyl, propyl, and butyl chlorides,bromides and iodides; dialkyl sulfates like dimethyl and diethylsulfate; and others.

In some embodiments, the compounds disclosed herein, such as thenucleosides and nucleotides, also include the prodrug derivativesthereof, which are covalently modified latent forms of thetherapeutically-active compound.

The term “prodrug” is used in its broadest sense and encompasses thosecompounds that when administered in a biological system are converted oractivated in vivo to therapeutically-active compounds by, for example, aspontaneous chemical reaction, a metabolic chemical reaction, an enzymecatalysed chemical reaction, and/or photolysis. Illustratively, aprodrug can be activated either by cellular enzymes or by chemicalcleavage such as hydrolysis to release (liberate) the nucleoside,nucleotide or nucleotide mimic after the prodrug enters cells. Examplesof prodrugs include compounds that can be oxidised, reduced, esterified,deesterified, alkylated, dealkylated, acylated, deacylated, aminated,deaminated, phosphorylated, dephosphorylated, photolyzed, and/orhydrolysed. Enzymes that may be capable of enzymatic conversion oractivation of a prodrug to a therapeutically-active compound include,for example, amidases, cholinesterases, esterases, lipases, nucleases,oxidases, phospholipases, phosphases, and/or reductases. Such prodrugmodification may improve or enhance, for example, drug absorption,solubility, lipophilicity, bioavailability, efficacy, and/or drugdelivery into cells.

Prodrug derivatives of the compounds of the present disclosure may beprepared by modification of the sugar moiety or of the phosphate orphosphate mimic to include a prodrug substituent. A prodrug may alsoinclude a labile protecting group on the functional moiety ortherapeutically-active compound as described herein. In addition tothose described herein, prodrug derivatives of nucleosides, nucleotidesand nucleotide phosphate mimics and methods of making the prodrugsappropriate for use in the present disclosure are described, inter alia,in PCT Publications WO 2003/072757 and WO 2003/073989 and U.S. Patentapplication publication US20020361177.

Prodrugs are compounds that are pharmacologically inert but areconverted by enzyme or chemical action to an active form of the drug(i.e., an active pharmaceutical ingredient) at or near the predeterminedtarget site. In other words, prodrugs are inactive compounds that yieldan active compound upon metabolism in the body, which may or may not beenzymatically controlled. Prodrugs may also be broadly classified intotwo groups: bioprecursor and carrier prodrugs. Prodrugs may also besubclassified according to the nature of their action. Bioprecursorprodrugs are compounds that already contain the embryo of the activespecies within their structure, whereby the active species are producedupon metabolism. For example, the first prodrug, antibacterialprontosil, is metabolized in vivo to its active metabolitesulphanilamide. Carrier prodrugs are formed by combining the active drugwith a carrier species forming a compound having desirable chemical andbiological characteristics, whereby the link is an ester or amide sothat the carrier prodrug is easily metabolized upon absorption ordelivery to the target site. For example, lipophilic moieties may beincorporated to improve transport through membranes. Carrier prodrugslinked by a functional group to carrier are referred to as bipartateprodrugs. Prodrugs where the carrier is linked to the drug by a separatestructure are referred to as tripartate prodrugs, whereby the carrier isremoved by an enzyme-controlled metabolic process, and whereby thelinking structure is removed by an enzyme system or by a chemicalreaction. (Thomas G, Medicinal Chemistry: An Introduction, 2000, JohnWiley & Sons, Ltd. pp. 12, 17, 243 and 364-372)(See also, Wermuth C G,2003, The Practice of Medicinal Chemistry, 2nd Ed., Academic Press33:561-582). Hydroxy-protecting group refers to any suitable group, suchas tert-butyloxy-carbonyl (t-BOC) and t-butyl-dimethyl-silyl (TBS).Other hydroxy protecting groups are shown in Hanson J R, 1999,Protecting Groups in Organic Synthesis, Sheffield Academic Press,2:8-35, which is incorporated herein by reference.

Illustratively, when administered to a host, a prodrug is generallyadministered as a pharmaceutically-acceptable prodrug that ismetabolised to form the therapeutically-active compound and the prodrugmoiety or substituent through, for example, hydrolysis or oxidation byenzymatic activity or by acid or base solvolysis. A “prodrug moiety” or“prodrug substituent” refers to the labile group that is removed fromthe therapeutically-active compound through a metabolic, hydrolytic,and/or enzymatic process. However, non-pharmaceutically-acceptableprodrugs also fall within the scope of the present disclosure and may beuse used, for example, in in vitro assays to improve solubility and/oras intermediates in the preparation of pharmaceutically-acceptableprodrugs or other compounds.

Illustrative prodrugs moieties include, but are not limited to residuesof: proteins; antibiotics; D- and L-amino acids which may be attached toa phosphate moiety or a phosphate mimic moiety via a carbon atom(phosphonates), a nitrogen atom (phosphoamidates), or an oxygen atom(phosphoesters) or may be attached to the sugar moiety through any oneor more of the R¹-R⁵ groups; peptides (preferably up to 10 amino acids)attached to a phosphate moiety or a phosphate mimic moiety via a carbonatom (phosphonates), a nitrogen atom (phosphoamidates), or an oxygenatom (phosphoesters), or may be attached to the sugar moiety through anyone or more of the R¹-R⁵ groups; drug moieties attached to a phosphatemoiety or a phosphate mimic moiety via a carbon atom (phosphonates), anitrogen atom (phosphoamidates), or an oxygen atom (phosphoesters), ormay be attached to the sugar moiety through any one or more of the R¹-R⁵groups; as well as including steroids; vitamins; polyamines;carbohydrates; polyethylene glycols (PEGs); cyclosaligenyls; substituted4 to 8-membered rings, with or without heteroatom substitutions,1,3-phosphoamidate attachments to a terminal phosphate or phosphatemimic moiety (γ or β) or connecting between an α,β or β,γ of a phosphatemoiety or phosphate mimic moiety, and so on. Phosphoesters andphosphoamidates are particularly preferred prodrug moieties.

In one embodiment, the prodrug of a nucleoside 5′-mono-phosphate mimiccan mask the negative charges of the phosphate mimic moiety entirely orpartially, or mask the negative charges of the di-phosphate mimic ortri-phosphate mimic moiety or phosphate moiety in order to, for example,enhance drug absorption and/or drug delivery into cells.

In another embodiment one or more prodrug substituents or moieties maybe attached to one or more X^(2′), X^(3′) and X^(5′) positions on anucleoside mono-phosphate mimic or to one or more X⁷-X¹⁰ positions on anucleoside di- or tri-phosphate mimic. Illustrative prodrug substituentsin positions X^(2′), X^(3′) or X^(5′) position include2,3-O-diacylglyceryloxy, 2,3-O-dialkylglyceryloxy,1-O-alkyl-2-O-acylglyceryloxy, 1-O-acyl-2-O-alkylglyceryloxy,1-S-alkyl-2-O-acyl-1-thioglyceryloxy, acyloxymethoxy,S-acyl-2-thioethoxy, S-pivaloyl-2-thioethoxy, acyloxymethoxy,pivaloyloxymethoxy, alkoxycarbonyloxymethoxy, S-alkyldithio-S′-ethyoxyacyloxymethoxy, S-acyl-2-thioethoxy, S-pivaloyl-2-thioethoxy,pivaloyloxymethoxy, alkoxycarbonyloxymethoxy, andS-alkyldithio-S′-ethyoxy.

In a further embodiment, the prodrug substituent is a substituent on ahydroxyl group of the sugar moiety (that is, for instance, any one ofR¹-R⁵). Illustratively, the modification results in the formation of anester and in this regard the preferred prodrug substituents areC₁-C₆acyl groups for example, acetyl, propionyl, pivaloyl, etc. Alsopreferred are substituted C₁-C₆ acyl moieties, for example,fluoroacetyl, difluoroacetyl, etc. More preferably the substituted C₁-C₆acyl group is represented as a residue of an L or D amino acidconsisting of alanine, asparagine, cysteine, glutamine, glycine,isoleucine, leucine, methionine, phenylalanine, proline, serine,threonine, tryptophan, tyrosine, valine, aspartic acid, glutamic acid,arginine, histidine, and lysine. Most preferably the prodrug substituentis an amino acid residue of D or L-valine.

The pharmaceutically suitable oral carrier systems (also referred to asdrug delivery systems, which are modern technology, distributed with oras a part of a drug product that allows for the uniform release ortargeting of drugs to the body) preferably include FDA-approved and/orUSP-approved inactive ingredients. Under 21 CFR 210.3(b)(8), an inactiveingredient is any component of a drug product other than the activeingredient. According to 21 CFR 210.3(b)(7), an active ingredient is anycomponent of a drug product intended to furnish pharmacological activityor other direct effect in the diagnosis, cure, mitigation, treatment, orprevention of disease, or to affect the structure or any function of thebody of humans or other animals. Active ingredients include thosecomponents of the product that may undergo chemical change during themanufacture of the drug product and be present in the drug product in amodified form intended to furnish the specified activity or effect. Asused herein, a kit (also referred to as a dosage form) is a packagedcollection of related material, including packages that are adapted, forexample, for once daily administration of a dosage form.

As used herein, the oral dosage form includes capsules (a solid oraldosage form consisting of a shell and a filling, whereby the shell iscomposed of a single sealed enclosure, or two halves that fit together,which are sometimes sealed with a band, and whereby capsule shells maybe made from gelatin, starch, cellulose, or other suitable materials,may be soft or hard, and are filled with solid or liquid ingredientsthat can be poured or squeezed), capsule or coated pellets (solid dosageform in which the drug is enclosed within either a hard or soft solublecontainer or “shell” made from a suitable form of gelatin; the drugitself is in the form of granules to which varying amounts of coatinghave been applied), capsule coated extended release (a solid dosage formin which the drug is enclosed within either a hard or soft solublecontainer or “shell” made from a suitable form of gelatin; additionally,the capsule is covered in a designated coating, which releases a drug ordrugs in such a manner to allow at least a reduction in dosing frequencyas compared to drug or drugs presented as a conventional dosage form),capsule delayed release (a solid dosage form in which the drug isenclosed within either a hard or soft soluble container made from asuitable form of gelatin, which releases a drug (or drugs) at a timeother than promptly after administration, whereby enteric-coatedarticles are delayed release dosage forms), capsule delayed releasepellets (solid dosage form in which the drug is enclosed within either ahard or soft soluble container or “shell” made from a suitable form ofgelatin); the drug itself is in the form of granules to which entericcoating has been applied, thus delaying release of the drug until itspassage into the intestines), capsule extended release (a solid dosageform in which the drug is enclosed within either a hard or soft solublecontainer made from a suitable form of gelatin, which releases a drug ordrugs in such a manner to allow a reduction in dosing frequency ascompared to that drug or drugs presented as a conventional dosage form),capsule film-coated extended release (a solid dosage form in which thedrug is enclosed within either a hard or soft soluble container or“shell” made from a suitable form of gelatin; additionally, the capsuleis covered in a designated film coating, which releases a drug or drugsin such a manner to allow at least a reduction in dosing frequency ascompared to drug or drugs presented as a conventional dosage form),capsule gelatin coated (a solid dosage form in which the drug isenclosed within either a hard or soft soluble container made from asuitable form of gelatin; through a banding process, the capsule iscoated with additional layers of gelatin so as to form a complete seal),capsule liquid filled (a solid dosage form in which the drug is enclosedwithin a soluble, gelatin shell which is plasticized by the addition ofa polyol, such as sorbitol or glycerin, and is therefore of a somewhatthicker consistency than that of a hard shell capsule; typically, theactive ingredients are dissolved or suspended in a liquid vehicle),granule (a small particle or grain), pellet (a small sterile solid massconsisting of a highly purified drug, with or without excipients, madeby the formation of granules, or by compression and molding), pelletscoated extended release (a solid dosage form in which the drug itself isin the form of granules to which varying amounts of coating have beenapplied, which releases a drug or drugs in such a manner to allow areduction in dosing frequency as compared to that drug or drugspresented as a conventional dosage form), pill (a small, round soliddosage form containing a medicinal agent intended for oraladministration), powder (an intimate mixture of dry, finely divideddrugs and/or chemicals that may be intended for internal or externaluse), elixir (a clear, pleasantly flavored, sweetened hydroalcoholicliquid containing dissolved medicinal agents; it is intended for oraluse), chewing gum (a sweetened and flavored insoluble plastic materialof various shapes which when chewed, releases a drug substance into theoral cavity), syrup (an oral solution containing high concentrations ofsucrose or other sugars; the term has also been used to include anyother liquid dosage form prepared in a sweet and viscid vehicle,including oral suspensions), tablet (a solid dosage form containingmedicinal substances with or without suitable diluents), tablet chewable(a solid dosage form containing medicinal substances with or withoutsuitable diluents that is intended to be chewed, producing a pleasanttasting residue in the oral cavity that is easily swallowed and does notleave a bitter or unpleasant after-taste), tablet coated (a solid dosageform that contains medicinal substances with or without suitablediluents and is covered with a designated coating), tablet coatedparticles (a solid dosage form containing a conglomerate of medicinalparticles that have each been covered with a coating), tablet delayedrelease (a solid dosage form which releases a drug or drugs at a timeother than promptly after administration, whereby enteric-coatedarticles are delayed release dosage forms), tablet delayed releaseparticles (a solid dosage form containing a conglomerate of medicinalparticles that have been covered with a coating which releases a drug ordrugs at a time other than promptly after administration, wherebyenteric-coated articles are delayed release dosage forms), tabletdispersible (a tablet that, prior to administration, is intended to beplaced in liquid, where its contents will be distributed evenlythroughout that liquid, whereby term ‘tablet, dispersible’ is no longerused for approved drug products, and it has been replaced by the term‘tablet, for suspension’), tablet effervescent (a solid dosage formcontaining mixtures of acids, e.g., citric acid, tartaric acid, andsodium bicarbonate, which release carbon dioxide when dissolved inwater, whereby it is intended to be dissolved or dispersed in waterbefore administration), tablet extended release (a solid dosage formcontaining a drug which allows at least a reduction in dosing frequencyas compared to that drug presented in conventional dosage form), tabletfilm coated (a solid dosage form that contains medicinal substances withor without suitable diluents and is coated with a thin layer of awater-insoluble or water-soluble polymer), tablet film coated extendedrelease (a solid dosage form that contains medicinal substances with orwithout suitable diluents and is coated with a thin layer of awater-insoluble or water-soluble polymer; the tablet is formulated insuch manner as to make the contained medicament available over anextended period of time following ingestion), tablet for solution (atablet that forms a solution when placed in a liquid), tablet forsuspension (a tablet that forms a suspension when placed in a liquid,which is formerly referred to as a ‘dispersible tablet’), tabletmultilayer (a solid dosage form containing medicinal substances thathave been compressed to form a multiple-layered tablet or atablet-within-a-tablet, the inner tablet being the core and the outerportion being the shell), tablet multilayer extended release (a soliddosage form containing medicinal substances that have been compressed toform a multiple-layered tablet or a tablet-within-a-tablet, the innertablet being the core and the outer portion being the shell, which,additionally, is covered in a designated coating; the tablet isformulated in such manner as to allow at least a reduction in dosingfrequency as compared to that drug presented as a conventional dosageform), tablet orally disintegrating (a solid dosage form containingmedicinal substances which disintegrates rapidly, usually within amatter of seconds, when placed upon the tongue), tablet orallydisintegrating delayed release (a solid dosage form containing medicinalsubstances which disintegrates rapidly, usually within a matter ofseconds, when placed upon the tongue, but which releases a drug or drugsat a time other than promptly after administration), tablet soluble (asolid dosage form that contains medicinal substances with or withoutsuitable diluents and possesses the ability to dissolve in fluids),tablet sugar coated (a solid dosage form that contains medicinalsubstances with or without suitable diluents and is coated with acolored or uncolored water-soluble sugar), osmotic, and the like.

The oral dosage form composition contains an active pharmaceuticalingredient and one or more inactive pharmaceutical ingredients such asdiluents, solubilizers, alcohols, binders, controlled release polymers,enteric polymers, disintegrants, excipients, colorants, flavorants,sweeteners, antioxidants, preservatives, pigments, additives, fillers,suspension agents, surfactants (e.g., anionic, cationic, amphoteric andnonionic), and the like. Various FDA-approved topical inactiveingredients are found at the FDA's “The Inactive Ingredients Database”that contains inactive ingredients specifically intended as such by themanufacturer, whereby inactive ingredients can also be considered activeingredients under certain circumstances, according to the definition ofan active ingredient given in 21 CFR 210.3(b)(7). Alcohol is a goodexample of an ingredient that may be considered either active orinactive depending on the product formulation.

In addition to using prodrug approaches, the delivery of the compoundsdescribed herein including the nucleosides and/or nucleotides may beassisted by using a therapeutically acceptable carrier such as liposomalsuspensions, cationic lipids, and polyimines.

The nucleosides of the present disclosure can be prepared by those whoare skilled in synthetic organic and nucleoside chemistry usingestablished synthetic methodology (Chemistry of Nucleosides andNucleotides Vol. 1, 2, 3, edited by Townsend, Plenum Press; Handbook ofNucleoside Synthesis by Vorbrüggen Ruh-Pohlenz, John Wiley & Sons, Inc.,2001; The Organic Chemistry of Nucleic Acids by Yoshihisa Mizuno,Elsevier, 1986). If required, nucleosides of the present disclosure canbe converted to their corresponding mono-phosphate, di-phosphate, andtri-phosphate by established phosphorylation procedures.

Schemes A-D illustrate chemical processes and transformations that maybe useful for the preparation of compounds in the present disclosure,such as compounds of formula I and similar compounds.

Glycosyol pyrrolo-triazines can be prepared by glycosylation of intactpyrrolo-triazines as shown in Scheme A. Conditions used for suchglycosidations are well known to practitioners in the art.

In Scheme A, preferably A is —O—, —CH₂— or optionally protected —N—; R²,R^(2′), R³, R^(3′), R^(4′) are each independently —H, halogen, alkyl,—O-alkyl, —OH, optionally protected —O, methyl, or —F; R⁵ is anoptionally protected —OH or —NH₂; Lv is a leaving group; and Q isindependently halogen, —H, —OH, —SH, —CN, S(C₁-C₄alkyl), —NO₂, NH₂,—NHNH₂, —N₃, —NR′R′ wherein each R′ is independently H or C₁-C₄ alkyl,—C(S)NH₂, —CH₃, —CH₂OH, —CH₂NH₂, —CH₂NH₃ ⁺, —COOH, —COOCH₃, —COOCH₂CH₃,—CONHCH₃, —CONH₂, —CF₃, —N(CH₃)₂, —NHCOCH₃, —NHCONH₂, —NHCNHNH₂, —ONH₂,—CH₂OCH₃, —O(CH₂)CH₃, COOC₁-C₄alkyl, optionally substituted alkyl,optionally substituted alkenyl, optionally substituted alkynyl,optionally substituted aryl, optionally substituted acyl, optionallysubstituted arylalkyl, optionally substituted cycloalkyl, optionallysubstituted cycloalkenyl, optionally substituted phenyl, optionallysubstituted heteroaryl, optionally substituted heterocyclyl, optionallysubstituted alkyloxy, optionally substituted alkenyloxy, optionallysubstituted alkynoxy, optionally substituted aryloxy, optionallysubstituted acyloxy, optionally substituted oxyacyl, optionallysubstituted arylalkoxy, optionally substituted heterocycloxy, optionallysubstituted heteroaryloxy, optionally substituted cycloalkoxy,optionally substituted cycloalkenoxy, optionally substituted amino,optionally substituted aminoacyl, optionally substituted aminoacyloxy,optionally substituted acylamino, optionally substituted oxyacylamino,optionally substituted oxyacyloxy, optionally substituted acylimino,optionally substituted acyliminoxy, optionally substituted oxyacylimino,optionally substituted aminothioacyl, optionally substitutedthioacylamino, optionally substituted aminosulfinyl, optionallysubstituted aminosulfonyl, optionally substituted thio, optionallysubstituted thioalkyl, optionally substituted thioacyl, optionallysubstituted thioacyloxy, optionally substituted oxythioacyl, optionallysubstituted oxythioacyloxy, optionally substituted phosphorylamino,optionally substituted sulfinyl, optionally substituted sulfonyl,optionally substituted sulfinylamino, optionally substitutedsulfonylamino, optionally substituted oxysulfinylamino, optionallysubstituted oxysulfonylamino, thiazole, oxazole, imidazole, imidazoline,triazole, and tetrazole.

The compounds described herein can also be converted into theircorresponding mono-phosphates, di-phosphates, and tri-phosphates usingwell established methods. Furthermore, as discussed above, prodrugs ofmono-phosphates, di-phosphates, and tri-phosphates can be prepared inorder to optimise the biological efficacy of these phosphorylatedcompounds. Methods for preparing such prodrugs are well known in the art(see, for example, Wagner, C. R., et al. Med. Res. Rev., 2000, 20,417-451).

In Scheme B, preferably A is —O—, —CH₂—, or optionally protected R^(1′),R², R^(2′), R³, R^(3′), R^(4′) are each independently —H, halogen,alkyl, —O-alkyl, —OH, optionally protected —O—, or methyl, and Base isas described herein.

As discussed earlier, an alternative to the use of phosphates is the useof phosphate mimics and their prodrugs. One such phosphate mimic isshown below and can be prepared using appropriately protectednucleosides and known conditions.

In Scheme C, preferably A is —O—, —CH₂—, or optionally protected —N—;R^(1′), R², R^(2′), R³, R^(3′), R^(4′) are each independently —H,halogen, alkyl, —O-alkyl, —OH, optionally protected —O—, methyl, or —F;X′ is —O—, —S—, —NH—, —CF₂—, —CHF—, —CClH—, —CBr₂—, or —CHBr—. Base isas described herein.

Compound 1 may be produced using methods generally known to thoseskilled in the art, such as the procedures described in Hely. Chim.Acta, vol. 78, p. 486 (1995) and in U.S. Pat. No. 6,777,395. Briefly, toCompound A, H₂SO₄ and MeOH were added and then chilled to 0-4° C. andNaH was added followed by DCBCl and DMF to render Compound B. ToCompound B were added SnCl₂ and DCM, after which the mixture was chilledto 3° C. and distilled H₂O added to render Compound C. To Compound C wasadded Dess Martin periodinane followed by DCM to render Compound D. ToCompound D was added MeMgBr and Et₂O and the mixture was raised from−75° C. to −10° C. to render Compound 1. To Compound 1, trifluoroaceticacid was added, followed by distilled H₂O and then the mixture wasincubated at 60° C. for 8 h to render Compound E.

The compounds of the present disclosure may be tested for biologicalactivity using well known procedures. For example, antiviral assays maybe conducted according to published, widely used protocols. In order toobtain the therapeutic index, compound-induced cytotoxicity to hostcells may also measured in parallel with antiviral activities. Todetermine the mode of action of antiviral nucleosides the correspondingnucleoside tri-phosphates may be subjected to enzyme-based assays forthe inhibition of viral polymerases according to known protocols(Ranjith-Kumar et al. J. Viral. 2001, 75, 8615; Dhanak et al. J. Biol.Chem. 2002, 277, 38322-38327). Some compounds of the present disclosureshowed K, values of less than 1 μM against HCV NS5B.

Since the replicon RNA replication mimics the replication of HCV RNA ininfected hepatocytes, compounds that have the inhibitory effects inreplicon assays are potentially useful as anti-HCV drugs. The HCVreplicon-containing cell lines (Randall and Rice, Current Opinion inInfectious Diseases 2001, 14, 743) may be used for the identification ofpotential anti-HCV compounds. Among them is a widely used subgenomicreplicon system developed by Lohmann et al. (Science 1999, 285, 110; JGeneral Virol. 2000, 81, 1631; J Virol. 2001, 75, 1437, 2002, 76, 4008).Some compounds of the present disclosure showed potent anti-HCV activitywith EC₅₀ values of low μM and below 1 μM.

Immortalized cell lines derived from hepatocytes, such as the Huh7 cellsused in replicon-containing cell lines, are known to have diminishedmetabolic activity. Therefore the assessment of the intrahepatocytelevels of therapeutically active entities that are generatedintracellularly by anabolic or catabolic processes requires assessmentin primary hepatocytes. Some compounds of the present disclosure showedhigher levels of intracellular triphosphate anabolite in primaryhepatocytes compared with replicon-containing cells.

Widely used protocols developed by Korba et al. (Antiviral Res. 1992,19, 55), and Pai et al. (Antimicrobial Agents Chemother. 1996, 40, 380)may be useful for the determination of in vitro anti-HBV activity.

Anti-HIV assays can be conducted according to the protocols developed bySchinazi et al. (Antimicrobial Agents Chemother. 1990, 34, 1061; 1992,36, 2423; 1993, 37, 875) or other widely used protocols (Kimpton et al.J. Virol. 1992, 66, 2232; Chan et al. J. Med. Chem. 2001, 44, 1866).Illustrative nucleoside tri-phosphates of the present disclosure may actas potent inhibitors of the non-structural position 5B (NS5B), which isHCV's RNA-dependent RNA polymerase. Accordingly, such compounds may besuited to treat HCV and/or inhibit or prevent replication of HCV in ahost. Also, compounds of the present disclosure may exhibit profiles ofactivity and may provide the artisan with an alternative to treatingviruses that exhibit drug resistance to conventional drugs. Othercompounds of the present disclosure may also reduce toxicity andtolerability levels relative to existing therapies and those indevelopment, and/or improve pharmacokinetic properties.

Accordingly, nucleosides, nucleotide, nucleotide mimics, and/or theirprodrugs of the present disclosure can be useful for the inhibition of avariety of enzymes including, but not limited to, DNA or RNApolymerases, helicases, ribonucleotide reductases, protein kinases, andtelomerases and for the modulation of G-proteins, P2 purinergicreceptors and the allosteric sites of a variety of enzymes.Illustratively, the nucleosides, nucleotides, nucleotide mimics and/orprodrugs of the present disclosure are used to treat viral infectionscaused by the RNA viruses of the group Flaviviridae and, in particular,HCV.

Also, the nucleosides, nucleotide mimics and/or their prodrugs andderivatives thereof that display cytotoxicity to fast-dividing cancercells may be useful for the treatment of proliferative disorders,including, but not limited to, lung cancer, liver cancer, prostatecancer, colon cancer, breast cancer, ovarian cancer, melanoma, andleukemia.

As the ligands of P2 receptors and G-proteins, as well as the inhibitorsof protein kinases, the nucleosides, nucleotides, nucleotide mimicsand/or their prodrugs of the present disclosure may also be useful forthe treatment of a wide range of other diseases and disorders such asinflammatory diseases, autoimmune diseases, Type 2 diabetes, andcardiovascular diseases.

To address the issue of drug resistance, combination therapies arewidely used in the treatment of infectious diseases and/or proliferativedisorders. One or more nucleosides, nucleotides, nucleotide mimics,prodrugs, and/or pharmaceutically-acceptable salts, esters, solvates,hydrates and prodrugs of the present disclosure may also betherapeutically administered as a single formulation, such as a singletablet or a solution for injection, with one or more chemical entities,or alternatively may be administered in separate formulations incombination with one or more other active chemical entities, to form acombination therapy. The other active chemical entities may include asmall molecule, a polypeptide, and/or a polynucleotide, andcombinations, salts, esters, solvates, hydrates and prodrugs and/orother derivatives thereof. When administered as separate formulations,the individual compounds may be co-administered at substantially thesame time, for example, administering two individual tablets, oradministered separately at different times and/or at differentfrequencies. Illustratively, the dose administered to a host for eachcompound is generally determined by the desired blood levelconcentration of drug over a predetermined amount of time to achieve atherapeutic affect in the host, as know in the art and further describedherein. For instance, compounds of this disclosure may be useful whenused in combination with other agents known to exert antiviral and/orantiproliferative effect. For example, combination withimmunomodulatory/antiviral agents such as an interferon and/or aninterferon derivative such as interferon alpha 2B (such as Intron® Ainterferon available from Schering Corp., Kenilworth, N.J.), pegylatedinterferon alpha 2A (such as Pegasys® available from Hoffmann-LaRoche,Nutley, N.J.), pegylated interferon alpha 2B (such as Peg-Intron™available from Schering Corp., Kenilworth, N.J.), consensus interferon(such as interferon alphacon-1, or Infergen® available from ValeantPharmaceuticals, Costa Mesa, Calif.), interferon alpha 2A, recombinantinterferon alpha 2A (such as Roferon interferon available fromHoffmann-LaRoche, Nutley, N.J.), or lymphoblastoid interferon tau, andother large or small molecules known to modulate host immune responsesmay be beneficial in the treatment of a viral infection.

Similarly, combinations of compounds of this disclosure with inosinemono-phosphate dehydrogenase (IMPDH) inhibitors, antiviral nucleosides,and/or antiviral non-nucleosides could augment the activity of thenucleosides or nucleotides disclosed herein when administered alone.Other illustrative combinations useful in present disclosure includecombinations with, for example, a cyclosporine such as, cyclosporin A; acytokine, such as, interleukin 2, interleukin 6, or interleukin 12; atype 1 helper T cell response enhancer; interfering RNA; anti-sense RNA;an imidazoquinolone, such as resimiquimod or Imiqimod; an inosine5′-monophospate dehydrogenase inhibitor; ribavirin; amantadine;rimantadine; and/or a metalloprotease, serine protease, polymerase, or ahelicase inhibitory agent; and combinations thereof. In one embodiment,one or more compounds of the present disclosure are used in combinationwith one or more compounds having anti-HCV activity including, forexample, a HCV helicase inhibitor, a HCV metalloprotease inhibitor, aHCV polymerase inhibitor, a HCV NS4B protein inhibitor, a HCV NS5Aprotein inhibitor, a HCV serine protease inhibitor, and/or a HCV entry,assembly, or egress protein inhibitor.

The present disclosure also relates to kits or packages adapted foradministration of the particular dosage regimen, to ease mixing and/oradministration of a composition disclosed herein. Illustratively, amonth's supply of tablets can be packaged in a tablet dispenser such asa DIALPAK® tablet dispenser supplied by Ortho, Inc., which contains adial member at the center of a circle that points to a day of the weekso that when a pill is removed from the dispenser, the dial can berotated so that it points to the next day of the week. This design isintended to avoid the inadvertent taking of two pills in one day and isalso designed to let the owner of the device know when a day has beenskipped. A further illustration includes supplying a month's supply ofpowder that is packaged with a separate month's supply of diluent and are-usable plastic dosing cup. One skilled in the art will appreciatethat such kits may contain many different variations of the abovecomponents, such as, for example, kits that are packaged in a unit doseform or as daily, weekly or yearly kits.

Another aspect of the present disclosure is a method of inhibiting thefunction of the HCV replicon by contacting the HCV replicon with acompound of formula I or a pharmaceutically-acceptable salt, ester,solvate, hydrate or prodrug thereof.

Based upon the proceeding schemes and/or procedures and the followingExamples, substituted pyrrolo-triazines attached to a sugar moiety canbe prepared by one skilled in the art using similar methods, as shown inTable Nos. 1 and 2.

TABLE NO. 1 Substitutions of the glycosyl 4-amino pyrrolol-triazine,where R″, R″′, and R″″, may be independently selected.

R″, R″′, R″″

TABLE NO. 2 Substitutions of the glycosyl 4-keto pyrrolol-triazine,where R″, R″′, and R″″ may be independently selected.

R″, R″′, R″″

Abbreviations that may be used herein including the Schemes and theexperimental section are as follows unless indicated otherwise:

Ar: argon

Bn: benzyl

Bu: n-butyl

Bz: benzoyl

DCB: 2,4-dichlorobenzyl

DCM: dichloromethane

DIEA: diisopropylethylamine

DMF: dimethylformamide

DMSO: dimethyl lsulfoxide

ESI: electrospray ionization

Et: ethyl

EtOAc:ethyl acetate

HPLC: high performance liquid chromatography

Me: methyl

MeOH: methyl alcohol

MS: mass spectrometry

NMR: nuclear magnetic resonance

Ph: phenyl

RT: room temperature

TEA: triethylamine

TFA: trifluoroacetic acid

THF: tetrahydrofuran

The following non-limiting examples are put forth to provide those ofordinary skill in the art with a complete disclosure and description ofhow to prepare and use the compounds disclosed herein. The followingspecific embodiments are representative compounds of formula (1), andare therefore, to be construed as merely illustrative, and not limitingto the remainder of the disclosure in any way whatsoever.

Example 1 Preparation of4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 9)

Step i: Compound1,3,5-bis-O-(2,4-dichlorophenylmethyl)-1-O-methyl-2-C-methyl-D-ribofuranose(19.2 g) in anhydrous THF (200 mL) was chilled to 0° C. under Ar in anice water bath then treated with NaH (60% dispersion in oil, 2.6 g) in 4batches at 10 min intervals. The suspension was warmed to RT thentreated dropwise with 2,4-dichlorobenzyl chloride (11.2 mL). Thereaction was then heated to 70° C. under Ar for 16-24 h. The cooledreaction mixture was filtered, and the filtrate was eluted on silicawith 10-30% EtOAc:hexane to form Compound 2 as a mixture of α and βanomers (16.68 g): ¹H NMR (CDCl₃) major anomer: δ 1.42 (s, 3H); 3.46 (s,3H); 3.64 (d, 1H, J 4.8 Hz); 3.73 (dd, 1H, J 3.9, 10.7 Hz); 3.67 (dd,1H, J 4.4, 10.7 Hz); 4.29 (q, 1H, J 4.3 Hz); 4.56-4.85 (m, 7H);7.11-7.25 (m, 3H, J 2.0, 8.4 Hz); 7.31-7.41 (m, 5H); 7.58 (d, 1H, J 8.4Hz).

Step ii: Compound 2 (6.91 g) in TFA (70 mL) was chilled to 0° C. thentreated dropwise with water (7 mL). The mixture was warmed to RT thenstirred for 4 h. The resulting solution was concentrated to 10 mL andadded slowly to a 50:50 mixture of Et₂O:sat. NaHCO₃ (aq) (80 mL total).The mixture was neutralized with NaHCO₃ (aq), and the aqueous layer wasextracted with ether (2×50 mL), and then the combined organic extractswere washed with NaHCO₃ (aq). The organic extract was dried (MgSO₄),filtered, and concentrated in vacuo. The crude material was eluted on asilica column with 5-40% EtOAc:hexane to afford Compound 3 (5.2 g) as amixture of α and β anomers: ¹H NMR (d₆-acetone) both anomers: δ 1.52 (s,6H); 3.79 (t, 4H, J 4.8 Hz); 3.99 (d, 1H, J 5.6 Hz); 4.10 (d, 1H, J 7.3Hz); 4.21-4.27 (m, 1H); 4.37 (dd, 1H, J 4.5, 10.0 Hz); 4.62-4.95 (m,12H); 5.10 (d, 1H, J 9.1 Hz); 5.20 (d, 1H, J 4.6 Hz); 5.57 (d, 1H, J 4.8Hz); 5.62 (s, 1H); 7.25-7.70 (m, 18H).

Step iii: Compound 3 (5.52 g) in anhydrous DCM (40 mL) under Ar wastreated with trichloroacetonitrile (1.95 mL) and Cs₂CO₃ (254 mg) andstirred at RT for 3 h. The solution was diluted with DCM (50 mL), washedwith water (100 mL), and the aqueous layer extracted with DCM (2×50 mL).The combined organic extracts were washed with brine (100 mL), dried(MgSO₄), filtered, and concentrated. The resulting residue was elutedthrough a silica column with 15% EtOAc:hexane to give the targetcompound 4 (5.58 g) as a mixture of α and β anomers: ¹H NMR (CDCl₃)major anomers: δ 1.56 (s, 3H); 3.71 (dd, 1H, J 4.8, 10.8 Hz); 3.80 (dd,1H, J 4.0, 10.8 Hz); 4.15 (d, 1H, J 8.1 Hz); 4.42-4.91 (m, 7H); 6.25 (s,1H); 7.15-7.53 (m, 9H); 8.55 (s, 1H).

Step iv: Compound 4 (5.0 g) in anhydrous DCM (200 mL) was treated withpowdered 4 Å molecular sieves under Ar for 2 h. The solution was thenchilled to −70° C. (internal temperature), treated with freshlydistilled pyrrole (1.46 mL) then dropwise with BF₃-OEt₂ (2.76 mL). Themixture was stirred for 40 min, while maintaining the internaltemperature below −55° C. The mixture was then cooled to −70° C. andtreated with 7 M NH₃ in methanol (20 mL) before being warmed to RT. Themixture was diluted with DCM and washed with water. The organic extractwas dried (MgSO₄), filtered, and concentrated in vacuo to give a greygum. The crude material was applied to a silica flash column and elutedwith 15% EtOAc:hexane to afford the pyrrole nucleoside Compound 5 (2.72g) as a mixture of α:β anomers in a ratio of about 2:3: ¹H NMR (CDCl₃)β-anomer only: δ 9.53 (br s, 1H), 7.60-7.14 (m, 9H), 6.36-6.35 (m, 1H),6.11-6.10 (m, 1H), 6.04 (br s, 1H), 5.13 (s, 1H), 4.89-4.61 (m, 6H),4.37-4.36 (m, 1H), 4.21 (d, J 8.4 Hz, 1H), 4.10 (dd, J 2.6 Hz, 10.5 Hz,1H), 3.85 (dd, J 1.9 Hz, 10.5 Hz, 1H), 1.16 (s, 3H).

Step v: Compound 5 (1.37 g, mixture of anomers) was suspended inanhydrous acetonitrile (6 mL). Anhydrous DMF was added until ahomogeneous solution was observed (˜1.0 mL), and the solution waschilled under Ar in an ice:acetone bath to −12° C. After 10 min, thesolution was treated dropwise with chlorosulphonyl isocyanate (0.17 mL),and the resulting mixture was stirred below 0° C. for 45 min, duringwhich time a dark red colour was observed. The mixture was poured ontoice (100 g), diluted with EtOAc (100 mL), and stirred until the icemelted. The organic extract was dried (MgSO₄), filtered, andconcentrated in vacuo to give a dark pink oil. The crude material wassuspended in 20 mL 50:50 DCM:hexane, applied to a silica flash column,and eluted with 15-50% EtOAc:hexane to render Compound 6 as the β-anomer(0.69 g) with the corresponding α-anomer (0.28 g) collected separately:¹H NMR (CDCl₃)β-anomer: δ 10.44 (s, 1H), 7.53 (d, J 8.3 Hz, 1H), 7.47(d, J 2.0 Hz, 1H), 7.42-7.37 (m, 3H), 7.32-7.21 (m, 4H), 6.79 (dd, J2.6,3.8 Hz, 1H), 6.10 (dd, J 2.6 Hz, 3.5 Hz, 1H), 5.11 (s, 1H), 4.90 (d, J12.5 Hz, 1H), 4.85 (d, J 13.1 Hz, 1H), 4.74 (d, J 13.1 Hz, 1H), 4.73 (d,J 12.5 Hz, 1H), 4.68 (d, J 12.4 Hz, 1H), 4.59 (d, J 12.4 Hz, 1H), 4.35(ddd, J 1.9 Hz, 2.4 Hz, 8.4 Hz, 1H), 4.13 (d, J 8.4 Hz, 1H), 4.05 (dd, J2.8 Hz, 10.6 Hz, 1H), 3.76 (dd, J 1.7 Hz, 10.6 Hz, 1H), 1.20 (3H, s).

Step vi: NaH (72.5 mg) in dry THF (13 mL) was cooled to −5° C. for 10min. Compound 6 (0.6 g, β-anomer) in THF (2 mL) was added dropwisefollowed by portionwise addition of Ph₂P(O)ONH₂ (0.39 g) before stirringat 0° C. for 30 min. The mixture was partitioned between toluene andwater, and the organic extracts were collected, dried (MgSO₄), filtered,and concentrated in vacuo. The product was stored in the freezer andused in subsequent reactions without further purification: ¹H NMR(d₆-DMSO): δ 7.63 (br d, J 1.9 Hz, 1H), 7.58-7.54 (m, 4H), 7.45-7.33 (m,4H), 6.76 (d, J 4.4 Hz, 1H), 6.14 (d, J 4.4 Hz, 1H), 6.13 (br s, 2H),5.36 (s, 1H), 4.76-4.62 (m, 6H), 4.22-4.19 (m, 1H), 4.0 (d, J 7.0 Hz,1H), 3.83 (dd, J 3.5 Hz, 10.9 Hz, 1H), 3.76 (dd, J 4.4 Hz, 10.9 Hz, 1H),1.15 (s, 3H).

Step vii: to a solution of Compound 7 (60 mg) in anhydrous DMA (2 mL)was added formamidine acetate (700 mg), and the suspension heated underAr at 140° C. for 1.5 h. The mixture was cooled to RT and moreformamidine acetate (700 mg) was added, and the mixture was heated foranother 1.5 h at 140° C. The mixture was cooled to RT overnight,whereupon precipitation occurred. The supernatant was removed, and theprecipitate washed with DCM. The supernatant and combined washings wereconcentrated in vacuo. Residual DMA was distilled off (Kugelrohr), andthe residue taken up in DCM (5 mL), washed with water (1 mL), dried withMgSO₄, filtered, and concentrated. Residual DMA was removed bydistillation, and the residue was purified on flash silica gel (50%EtOAc in hexane) to afford Compound 8 (32 mg) as a colourless syrup: ¹HNMR (CDCl₃): δ 7.89 (s, 1H), 7.61 (d, J 8.3 Hz, 1H), 7.46 (d, J 8.3 Hz,1H), 7.38-7.19 (m, 6H), 7.15 (dd, J 2.1 Hz, 8.3 Hz, 1H), 6.82 (d, J 4.5Hz, 1H), 6.56 (d, J 4.5 Hz, 1H), 5.88 (s, 1H), 5.76 (br s, 2H), 4.86 (s,2H), 4.72 (s, 2H), 4.73-4.62 (m, 2H), 4.40-4.35 (m, 1H), 4.09 (d, J 8.3Hz, 1H), 3.97 (dd, J 2.7 Hz, 10.9 Hz, 1H), 3.81 (dd, J 3.7 Hz, 10.8 Hz,1H), 1.14 (s, 3H); ¹³C NMR (CDCl₃): δ 155.47, 147.18, 136.17, 134.65,134.60, 134.25, 134.10, 133.79, 133.54, 133.30, 132.66, 130.42, 130.24,130.17, 129.72, 129.39, 129.24, 128.84, 127.29, 127.26, 127.20, 114.43,110.86, 100.48, 85.06, 83.76, 79.43, 78.67, 70.22, 70.19, 70.10, 62.88,18.00.

Step viii: to a solution of Compound 8 (240 mg) in dry methanol (30 mL)was added, with stirring, anhydrous sodium acetate (192 mg) and glacialacetic acid (670 μL). The mixture was degassed, purged with Ar, and 10%Palladium on charcoal was added (150 mg). The mixture was stirred at 45°C. under H₂ for 66 h. The reaction mixture was degassed, purged with Ar,filtered through a pad of celite with MeOH, and concentrated to obtainthe crude product. Column chromatography on flash silica gel (17% MeOHin EtOAc) rendered Compound 9 (70.7 mg). ESI-MS m/z 281 ([M+H]⁺); ¹HNMR(d₆-DMSO) δ 7.81 (s, 1H), 7.61 (br s, 2H), 6.84 (d, J 4.4 Hz, 1H), 6.70(d, J 4.4 Hz, 1H), 5.39 (s, 1H), 4.90 (br s, 1H), 4.75 (br t, J 5.4 Hz,1H), 4.66 (s, 1H), 3.78-3.55 (m, 3H), 3.62-3.55 (m, 1H), 0.78 (s, 3H).

Example 2 Preparation of4-amino-5-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 11)

Step i: to a suspension of Compound 8 (0.11 g) in acetonitrile (2 mL)was added Selectfluor™(1-Chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octanebis(tetrafluoroborate) (80 mg), and the mixture was stirred andsonicated at RT for 5 min. The tube was sealed and heated in a microwavereactor at 82° C. for 15 min. The solvent was removed in vacuo to rendera dark brown gum. The crude product (Compound 10) was suspended in 2 mLDCM and applied to a silica flash column and eluted with 12%EtOAc/hexane to afford the product as a pale brown foam (30 mg): ¹H NMR(CDCl₃): δ 7.79 (s, 1H), 7.61 (d, J 8.4 Hz, 1H), 7.45 (d, J 8.2 Hz, 1H),7.45 (d, J 8.2 Hz, 1H), 7.41 (d, J 2.1 Hz, 1H), 7.37-7.34 (m, 3H),7.27-7.17 (m, 3H), 6.60 (s, 1H), 5.85 (s, 1H), 4.87 (s, 2H), 4.72 (s,2H), 4.69 (q, J 12.6 Hz, 2H), 4.36 (td, J 8.5 Hz, 2.9 Hz, 1H), 4.07 (d,J 8.5 Hz, 1H), 3.97 (dd, J 2.5 Hz, 10.9 Hz, 1H), 3.79 (dd, J 3.2 Hz,10.9 Hz, 1H), 1.16 (s, 3H).

Step ii: to a stirred suspension of Compound 10 (50 mg) in anhydrousmethanol (4 mL) was added sodium acetate (60 mg) and 10% Pd/C (40 mg).The mixture was hydrogenated at 45° C. for 16 h. The mixture wasfiltered to remove the catalyst and the filtrate was concentrated invacuo. The crude material was purified by column chromatography (5%MeOH/CH₂Cl₂) to afford Compound 10 (5.1 mg): ESI-MS m/z ([M+H]⁺) 299.16;¹H NMR (d₆-DMSO): δ 7.73 (s, 1H), 6.66 (s, 1H), 5.37 (s, 1H), 3.74-3.69(m, 3H), 3.60-3.57 (m, 1H), 0.80 (s, 3H).

Example 3 Preparation of4-amino-5-chloro-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 12)

Step i: Compound 9 (52 mg) in anhydrous DMF (2 mL) under Ar was chilledto 0° C. and treated dropwise with a solution of N-chlorosuccinimide inanhydrous DMF (27 mg in 1 mL). The mixture was warmed to RT and stirredfor 1 h. The mixture was concentrated then eluted through a silicacolumn with 0-10% MeOH:EtOAc to give Compound 12 (5.3 mg): ESI-MS m/z407.1 ([M+H]⁺); ¹H NMR (d₆-DMSO): δ 0.83 (s, 3H); 3.60 (m, 1H);3.70-3.74 (m, 4H); 4.74 (s, 1H); 4.84 (t, 1H, J=5.0 Hz); 4.91 (d, 1H,J=6.4 Hz); 5.36 (s, 1H); 6.86 (s, 1H); 7.83 (s, 1H).

Example 4 Preparation of4-amino-5-iodo-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 13)

Step i: to a solution of Compound 9 (5.2 mg) in anhydrous DMF (0.5 mL)was added at RT N-iodosuccinimide (4.7 mg), and the mixture was stirredin the dark at RT and under Ar for 4 d. Saturated sodium thiosulfatesolution was added (4 drops), and the resulting mixture was extractedwith EtOAc (3×1 mL). The organic phase was concentrated andfreeze-dried. The resulting residue was suspended in a small amount ofMeOH and purified on flash silica gel twice (elution gradient EtOAc to5% MeOH in EtOAc) to afford Compound 13 as a colorless solid (1.5 mg):ESI-MS m/z 407 ([M+H]⁺); ¹H NMR (300 MHz, d₆-DMSO): ¹H NMR (300 MHz,d₆-DMSO): δ 7.87 (s, 1H), 7.34 (br s, 2H), 7.01 (s, 1H), 5.35 (s, 1H),4.91 (br s, 1H), 4.82 (t, J 5.1 Hz, 1H), 4.72 (s, 1H), 3.77-3.66 (m,3H), 3.61-3.54 (m, 1H), 0.79 (s, 3H).

Example 5 Preparation of4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine-5-carbonitrile(Compound 14)

Step i: a solution of Compound 13 (20 mg) in anhydrous DMA (0.7 mL) wasevacuated and purged with Ar (three times). Zinc powder (1 mg),bis(tri-tert-butylphosphine)palladium(0) (3.2 mg) and zinc cyanide (18mg) were added, and the mixture was heated at 150° C. and under Ar withstirring for 1 h. The mixture was cooled to RT and solid phase boundtriphenylphosphine (PS-TPP, previously washed with DMA, 60 mg) wasadded, and the resulting mixture was stirred at RT under Ar for 21 h.The mixture was filtered through celite and washed with EtOH. Thefiltrate was concentrated, and residual DMA was removed by distillation(Kugelrohr) to render 25 mg of an oil. This material was purified twiceon flash silica gel eluting with 5% MeOH in EtOAc to afford the productas pale yellow solid (4 mg). This material was boiled briefly in 2 mLMeOH with 1 mg activated charcoal to afford Compound 14 (2.5 mg) as acolourless solid: ESI-MS m/z 306 ([M+H]⁺); ¹H NMR (300 MHz, d₆-DMSO): δ8.11 (s, 1H), 7.58 (br s, 2H), 7.35 (s, 1H), 5.37 (s, 1H), 4.95 (d, J6.5 Hz, 1H), 4.86 (t, J 4.8 Hz, 1H), 4.80 (s, 1H), 3.80-3.69 (m, 3H),3.64-3.57 (m, 1H), 0.81 (s, 3H).

Example 6 Preparation of4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine-5-carboxylicacid amide (Compound 15)

Step i: to a solution of Compound 14 (12 mg) in ethanol (4.8 mL) wasadded 0.7 mL 28% aqueous ammonia and 0.18 mL 30% hydrogen peroxide. Themixture was stirred in a sealed vial at RT for 19 h. The solvent wasremoved in vacuo, and the crude product was purified on flash silica geleluting with 10% MeOH in EtOAc to afford the product as pale yellowsolid (9.1 mg). This material was recrystallised from EtOAc/MeOH toafford Compound 15 (6.5 mg) as a colourless solid: ESI-MS m/z 324([M+H]⁺); ¹H NMR (500 MHz, d₆-DMSO): δ 10.38 (d, J 3.1 Hz, 1H), 8.07 (brs, 1H), 8.04 (d, J 3.1 Hz, 1H), 7.91 (s, 1H), 7.52 (br s, 1H), 7.23 (s,1H), 5.39 (s, 1H), 4.98 (d, J 7.4 Hz, 1H), 4.74 (s, 1H), 4.64 (t, J 5.8Hz, 1H), 3.82-3.73 (m, 2H), 3.71-3.66 (m, 1H), 3.55 (dd, J 7.1 Hz, 8.3Hz, 1H), 0.82 (s, 3H).

Example 7 Preparation of4-amino-5-trimethylsilanylethynyl-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 16)

Step i: to a solution of Compound 13 (43 mg, 0.11 mmol), triethylamine(32 μL, 0.42 mmol) and (trimethylsilyl)acetylene (0.12 mL, 1.1 mmol)were stirred in anhydrous DMF (0.40 mL) under Ar for 5 min, then CuI(5.2 mg, 27 μmol) and PdCl₂(PPh₃)₂ (8.1 mg, 12 μmol) were added, and theresulting mixture stirred at RT for 2 h. The reaction mixture wasfiltered, concentrated in vacuo, and purified by reverse-phase LCMS,affording Compound 16 (10 mg, 26%) as a beige solid: ESI-MS m/z 377.2([M+H]⁺) ¹H NMR (d₆-DMSO) δ 7.94 (s, 1H), 6.96 (s, 1H), 5.33 (s, 1H),3.76-3.55 (m, 4H), 0.79 (s, 3H), 0.24 (s, 9H).

Example 8 Preparation of4-Amino-5-ethynyl-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 17)

Step i: a solution of Compound 16 (2.0 mg, 5.3 μmol) in methanol (0.20mL) was stirred with MP-carbonate (2.9 mmol/g, 18 mg, 53 μmol) for 30min. The solution was decanted from the resin and concentrated in vacuo,affording rendering Compound 17 (0.45 mg, 28%) as a white solid: ESI-MSm/z 305.2 ([M+H]⁺); ¹H NMR (d₆-DMSO) δ 7.92 (s, 1H), 6.97 (s, 1H), 5.35(s, 1H), 4.91-4.73 (m, 3H), 4.38 (s, 1H), 3.76-3.57 (m, 4H), 0.80 (s,3H).

Example 9 Preparation of 4-amino-5-carboxylicacid-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 18)

To a solution of Compound 14 (3.5 mg) in methanol (1 mL) was added anaqueous solution of 5 M NaOH, and the mixture was heated at 70° C. for 5h. After cooling to RT, the solution was neutralized by addition of anaqueous solution 5 M hydrochloric acid. The aqueous mixture waslyophilized to leave a white solid. Methanol (5 mL) was added to theflask, and the suspension was filtered. The filtrate was concentrated invacuo to leave a white film (3 mg). Purification by preparative reversephase HPLC provided Compound 18 as a white solid (1 mg). ESI-MS m/z 325([M+H]⁺).

Example 10 Preparation of2,4-diamino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 20)

Step i: to a solution of Compound 7 (50 mg, 0.07 mmol) in DCM (3 ml)under Ar was cooled to −78° C. whereupon a solution of 1.0 M borontrichloride in DCM (900 μL, 0.9 mmol) was added dropwise over 5 min. Theresulting brownish/red solution was then stirred at −78° C. to −70° C.for 3 h and allowed to warm gradually to 0° C. over 3 h and left for 20h at 0° C. A further aliquot of 1.0 M boron trichloride in DCM (100 uL,0.1 mmol) was added and the reaction mixture warmed to RT and stirredfor 4 d whereupon a solution of DCM:methanol (5 ml, 1:1 v/v) was added.After 30 min, the reaction mixture was filtered and evaporated todryness. The crude material was dissolved in EtOAc (2 ml) with methanol(2 drops to aid dissolution) and purified by column chromatography onSilica eluting with 0-15% MeOH/EtOAc. The fractions containing theproduct (as indicated by LCMS) were combined and evaporated to drynessto afford Compound 19, which, owing to its instability, was usedimmediately in the subsequent reaction.

Step ii: to the solution of partially purified Compound 19 in anhydrousethanol (3 ml) under Ar was added guanidine carbonate (150 mg, 2.0 mmol)followed by triethylamine (100 μl, 0.726 mmol). The suspension washeated in a microwave reactor for 2 h at 160° C., whereupon the reactionmixture was filtered and evaporated to dryness. The crude material wassuspended in water (3 ml) and methanol (3 drops) and purified by reversephase preparative HPLC. The appropriate fractions were combined andlyophilised to give Compound 20 as a white solid as (3 mg): ESI-MS m/z296.06 ([M+H]⁺r); ¹H NMR (D3-CH₃CN): 0.92 (s, 3H), 3.86 (m, 4H), 5.22(s, 1H), 6.61 (d, 1H), 6.94 (d, 1H).

Example 11 Preparation of4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine-5-carbothioicacid amide (Compound 21)

Step i: to anhydrous EtOH (30 μl) was added P₂S₅ (7.30 mg, 0.02 mmol)and the mixture stirred in a sealed vial for 1 h at RT. To the reactionmixture was added a solution of Compound 14 (51 mg, 0.0033 mmol) inanhydrous EtOH. (30 μl). The mixture was heated in a sealed vial at 120°C. for 3 h and then cooled to RT, whereupon water was added and themixture extracted with DCM. The aqueous layer was concentrated todryness and the residue purified by column chromatography silica gel(elution gradient ethyl acetate to 17% methanol in ethyl acetate) toafford Compound 21: ESI-MS m/z 340 ([M+H]⁺).

Example 12 Preparation of4-amino-5-oxazol-2-yl-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 22)

Step i: to a solution of Compound 13 (60 mg, 0.148 mmol) in anhydrousDMA (2.5 ml) was added the stannyloxazole (120 μl, 0.573 mmol), and themixture was degassed and purged with Ar 5 times. Pd(P^(t)Bu₃)₂ (15 mg,0.029 mmol) was then added and the mixture heated at 150° C. for 1 h.The mixture was cooled to RT, and the DMA was removed by distillation(Kugelrohr). The residue was taken up in acetonitrile (10 ml) and thesolution extracted with hexane (10×20 ml). The acetonitrile phase wasconcentrated in vacuo, and the residue was purified on silica (elutiongradient ethyl acetate to 16% methanol in ethyl acetate) to affordCompound 22: ESI-MS m/z 348 ([M+H]⁺); ¹H NMR (300 MHz, d₆-DMSO): δ 10.1(br d, 1H, J 1.8 Hz), 8.24 (br d, J 1.8 Hz, 1H), 8.17 (d, J 0.9 Hz, 1H),7.94 (s, 1H), 7.40 (d, J 0.9 Hz, 1H), 7.33 (s, 1H), 5.40 (d, 0.5 Hz,1H), 4.94-4.88 (m, 2H), 4.75 (s, 1H), 3.80-3.72 (m, 3H), 3.64-3.57 (m,1H), 0.81 (s, 3H).

Example 13 Preparation of4-amino-5-thiazol-2-yl-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 23)

Step i: to a solution of Compound 13 (20 mg, 0.05 mmol) in DMA (2 ml)under Ar was added tributylstannylthiazole (0.2 ml, 0.64 mmol) andPd(PPh₃)₄ (2.85 mg, 0.002 mmol). The resultant solution was heated to60° C. overnight and then 80° C. for 4 h. Upon cooling to RT, the DMAwas removed by Kugelrohr distillation. The crude material was purifiedby normal phase silica gel chromatography (Biotage MPLC) to yieldCompound 23 as a white solid (2.5 mg): ESI-MS m/z 364.17 ([M+H]⁺).

Example 14 Preparation of4-amino-5-(3H-[1,2,3]triazol-4-yl)-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 24)

Step i: to a suspension of Compound 17 (1.0 mg, 3.3 μmol), sodium azide(6.6 mg, 99 μmol) in water (1.3 mL), and acetonitrile (0.2 mL) was addeda 0.1 M solution of sodium ascorbate in water (26 μL, 2.5 μmol),followed by a 0.1 M solution of CuSO₄.5H₂O (13.2 μL, 1.2 μmol). Themixture was stirred at 120° C. under microwave irradiation for 5 h. Thetriazole (Compound 24) was observed in the reaction mixture beforeconcentration of the residue in vacuo to afford the crude product:ESI-MS m/z 348.1 ([M+H]⁺).

Example 15 Preparation of4-Amino-6-fluoro-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazin-7-yl(Compound 32)

Step i: to a solution of 6 (1.3 g) in THF (15 mL) at −78° C. was addednBuLi (1.24 mL; 1.6 M in hexanes). After 15 minutes2-chloromethoxy-ethyl-trimethylsilane (0.48 mL) was added. The reactionmixture was warmed to ambient temperature and stirred for 15 hours.NH₄Cl_((aq)) (50 mL) added and the aqueous layer was extracted withethyl acetate (3×35 mL). The combined organics were washed with brine,dried (MgSO₄) and concentrated to leave a pale yellow oil (1.91 g).Purification by flash column chromatography on silica eluting with 15 to25% EtOAc/hexane afforded Compound 26 (1.39 g). Rf-0.3 in 15%EtOAc/hexane.

Step ii: to a solution of 26 (1.17 g) in DMF (20 mL) at ambienttemperature was added N-bromo succinimide (0.49 g) and the reactionmixture was left to stir. After 16 hours tlc analysis showed consumptionof 2 and the formation of a new spot. Methanol (5 mL) was added and thereaction mixture was concentrated to leave a viscous yellow oil (1.98 g)which was purified by flash column chromatography on silica eluting with10% EtOAc/hexane to leave Compound 27 (1.01 g) as pale yellow oil.

Step iii: to a solution of 27 (350 mg) in Et₂O/hexane (6 mL; 1:2) at−78° C. was added dropwise a solution of nBuLi (1.0 mL; 1.5 M inhexane). The reaction mixture was stirred for 15 minutes and then asolution of trimethyltin chloride (1.5 mL; 1.0 M in tetrahydrofuran) wasadded dropwise. The reaction mixture was slowly warmed to ambienttemperature over 70 minutes. Tlc analysis showed the disappearance of SM(Rf˜0.5 in 15% EtOAc/hexane) and the emergence of 2 new spots(Rf˜0.35—reduced bromopyrrole and Rf˜0.6—product). NH₄Cl_((aq)) (20 mL)was added and the aqueous layer was extracted with ethyl acetate (3×20mL) and the combined organics were washed with brine (20 mL), dried(MgSO₄) and concentrated to leave a yellow oil (510 mg). The crudestannane was dissolved in dichloromethane (8 mL) and xenon difluoride(71 mg), silver triflate (146 mg) and di tert butyl-4-methyl-pyridine(16 mg) were added at ambient temperature. After 10 minutes tlc analysisshowed the consumption of starting material and the appearance of a newspot (Rf˜0.3-10% EtOAc/hexane). NaHCO_(3 (aq)) (20 mL) was added and thereaction was extracted with dichloromethane (3×20 mL) and the combinedorganics were washed with brine (20 mL) dried (MgSO₄) and concentratedto leave a pale brown oil (410 mg). Purification was by flash columnchromatography on silica eluting with 1% to 3% to 6% to 10% EtOAc/hexaneto afford product 28 (65 mg) as an amorphous white solid.

Step iv: to a solution of 28 (60 mg) in THF (1.5 mL) was added asolution of TBAF (0.21 mL; 1.0 M in tetrahydrofuran) and the reactionplaced in a microwave reactor and heated to 75° C. for 45 minutes. Tlcanalysis showed the appearance of a new product (Rf−0.3 in 20%EtOAc/hexane). NH₄Cl_((aq)) (10 mL) was added and the aqueous layer wasextracted with ethyl acetate (3×15 mL). The combined organics werewashed with brine (10 mL), dried (MgSO₄) and concentrated to leave apale yellow oil (12 mg). Purification by flash column chromatography onsilica eluting with 100% hexane to 16% EtOAc/hexane afforded product 29(42 mg) as a white solid.

Step v: to a solution of 29 (27 mg) in THF (0.5 mL) at −5° C. was addedlithium hexamethyl disilazide (60 μL; 1.0 M in tetrahydrofuran). Thereaction mixture was warmed to ambient temperature over 15 minutes thendiphenylphosphinyl-hydroxylamine (13 mg) was added and the reactionmixture was stirred for 1 hour. Tlc analysis displayed a new spot ofvery similar Rf (0.26 in 20% EtOAc/hexane). H₂O (10 mL) was added andthe aqueous layer was extracted with ethyl acetate (3×15 mL). Thecombined organics were washed with brine (10 mL), dried (MgSO₄) andconcentrated to leave crude 30 (45 mg) which was used directly in thenext reaction.

Step vi: a suspension of 30 (28 mg) and formamidine acetate (290 mg) inpropan-1-ol (2.0 mL) was heated for 1 hour at 200° C. in a microwavereactor. A dark brown suspension resulted. LC/MS analysis showedconsumption of SM and product formation. A new spot was observed by tlc(Rf−0.35 in 40% EtOAc/hexane). The reaction mixture was concentrated toleave a brown oil which was purified by flash column chromatography onsilica eluting with 20% to 30% to 40% EtOAc/hexane affording 31 (21 mg)as an amorphous white solid.

Step vii: to a solution of 31 (20 mg) in methanol at ambient temperaturewas added sodium acetate (21 mg), acetic acid (4 drops) and palladium(27 mg; 10% on carbon). The atmosphere was evacuated and filled withhydrogen gas (repeated 3 times) and the reaction was left to stir at 45°C. After 16 hours the reaction mixture was analysed by LC/MS and shownto be complete. The reaction mixture was filtered through a 0.45 umsyringe filter and the residue washed with methanol (7 mL). The filtratewas concentrated to leave the crude product as a white solid (44 mg).Purification by flash column chromatography on silica eluting with 100%DCM to 10% MeOH/DCM to 20% MeOH/DCM afforded Compound 32 (3.5 mg) as awhite solid. Rf−0.5 in 20% MeOH/DCM; ¹H NMR (d₄-MeOD) δ 7.85 (s, 1H),6.63 (s, 1H), 5.57 (s, 1H), 3.99 (m, 2H), 3.85 (m, 2H), □1.02 (s, 3H);ES/MS: m/z 299.1 ([MH⁺]).

Example 16 Preparation of Bis-POM (pivaloyloxymethyl) prodrug of4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 34)

Step i: Compound9,4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(156 mg) in anhydrous DMF (2 mL) was treated with N,N-Dimethylformamidedimethyl acetal (730 uL) and the resulting solution heated in amicrowave reactor at 70° C. for 10 min. The mixture was cooled and thesolvent removed and the crude material purified on silica with 0-20%MeOH:DCM to afford Compound 33 (200 mg). ESI-MS m/z 336 ([M+H]⁺); ¹H NMR(d₆-CD₃CN) δ 8.87 (s, 1H), 7.99 (s, 1H), 6.84 (d, J 4.4 Hz, 1H), 6.75(d, J 4.4 Hz, 1H), 5.45 (s, 1H), 5.44 (br s, 1H), 4.09 (br s, 1H),3.8-3.9 (m, 3H), 3.55-3.75 (m, 2H), 3.20 (s, 3H), 3.19 (s, 3H), 0.87 (s,3H).

Step ii: Bis-POM phosphoric acid, was dissolved in DCM (20 mL) and DMF(2 drops) under an atmosphere of Ar. Oxalyl chloride (1.16 mL) was addeddropwise and the solution left to stir for 2 h before the solvent wasremoved under high vacuum to afford the phosphoryl chloride as a yellowoil. The residue was dissolved in anhydrous THF (1 mL) and addeddropwise to a solution of Compound 33 in pyridine (1 mL). The mixturewas stirred at room temperature for 5 d before saturated ammoniumchloride solution (5 mL) was added. The mixture was extracted with ethylacetate and the combined extracts dried (brine, Na₂SO₄), filtered, andconcentrated in vacuo. The crude residue was purified on silica with0-20% MeOH:DCM. Fractions were analysed by 1 cms and those containingBis-POM nucleoside compounds were combined and the solvent removed toafford a crude mixture. The crude mixture was subjected to hydrolysiswithout further purification. ESI-MS m/z 617 ([M+H]⁺), 645 ([M+H]⁺).

Step iii: The crude mixture containing Bis-POM nucleosides inacetonitrile (1.2 mL) was treated with HCl (1M, 0.6 mL) and the mixtureheated in a microwave reactor at 60° C. for 10 min. The reaction mixturewas diluted by adding water (1 mL) and DMSO (1.2 mL) then filtered.).Purification by preparative reverse phase HPLC (60% to 90% MeOH inwater:10% NH₄OAc buffer) afforded Compound 34 as a glassy solid (5.8mg). ESI-MS m/z 589 ([M+H]⁺), 611 ([M+Na]⁺); ¹H NMR (d₆-DMSO) δ 7.82 (s,1H), 7.66 (br s, 2H), 6.84 (d, J 4.4 Hz, 1H), 6.54 (d, J 4.4 Hz, 1H),5.63 (s, 2H), 5.59 (s, 2H), 5.43 (s, 1H), 5.18 (br s, 1H), 4.89 (br s,1H), 4.18-4.38 (m, 2H), 3.96 (br tr, J 6-8 Hz, 1H), 3.68 (d, J 8.7 Hz,1H), 1.17 (s, 9H), 1.16 (s, 9H), 0.78 (s, 3H).

Example 17 Preparation of4-amino-5-imidazole-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine(Compound 38)

Step i: ethylenediamine (600 μl) was added to Compound 14 (30 mg) andthe reaction placed in a microwave reactor and heated to 110° C. for 40minutes. The solvent was removed in vacuo. The crude material waspurified by column chromatography (100% EtOAc then 15% MeOH/EtOAc) toafford the reduced imidazole, Compound 35 (13.1 mg) as a white solid:ESI-MS m/z 349 ([M+H]⁺); ¹H NMR (300 MHz, d₆-DMSO): δ 11.90 (br d, J 3.5Hz, 1H), 7.88 (br d, J 3.6 Hz, 1H), 7.84 (s, 1H), 7.21 (s, 1H), 7.04 (s,1H), 5.38 (s, 1H), 4.95 (d, J 6.9 Hz, 1H), 4.71 (s, 1H), 4.65 (t, J 5.6Hz, 1H), 3.88-3.39 (m, 8H), 0.82 (s, 3H).

Step ii: Compound 35 (12 mg) and imidazole (21.1 mg) were combined andco-evaporated with acetonitrile three times. DMF (0.2 ml) followed by1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane (16.5 μl) was added andthe mixture was stirred at RT overnight. The solvent was removed invacuo. Hexane was added and the silyloxy protected Compound 36 wascollected (16 mg) and taken on to the next step without furtherpurification.

Step iii: 2-iodoxybenzoic acid (IBX, 14 mg) was added to a solution ofCompound 36 (22 mg) in DMSO (0.3 ml) and the mixture was heated at 45°C. for 3 h. The solvent was removed in vacuo. The yellow residue wassuspended in EtOAc and quenched with saturated aqueous sodiummetabisulfite, washed with 1M NaOH, dried (MgSO₄), filtered andconcentrated in vacuo. Purification by column chromatography (50%EtOAc/hexane) afforded the oxidized Compound 37 (7.5 mg).

Step iv: TBAF (3 mg) was added to a solution of Compound 37 (7.5 mg) inTHF (0.1 ml) and the mixture was stirred at RT for 5 minutes. Thesolvent was removed in vacuo and the mixture was purified by columnchromatography (100% EtOAc then 5% MeOH/EtOAc) to afford the deprotected4-amino-5-imidazole-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine,Compound 38 (1.2 mg) as a white solid: ESI-MS m/z 347 ([M+H]⁺); ¹H NMR(300 MHz, d₆-DMSO): δ 12.54 (br s, 1H), 11.43 (br s, 1H), 7.91 (br s,1H), 7.80 (s, 1H), 7.23 (m, 1H), 7.15 (s, 1H), 7.03 (m, 1H), 5.40 (s,1H), 4.98 (d, J 6.9 Hz, 1H), 4.74 (s, 1H), 4.67 (t, J 5.7 Hz, 1H),3.85-3.51 (m, 4H), 0.85 (s, 3H).

Example 18 Nucleoside 5′-mono-phosphates

To the appropriate nucleoside compound (0.156 mmol) (dried over P20s invacuum overnight) is added trimethyl phosphate (1.5 mL). The mixture isstirred overnight in a sealed container containing 4 A molecular sieves.It is then cooled to 0° C. and phosphorous oxychloride (35.8 I1L, 2.5eq.) is added via syringe. The mixture is stirred for 3 h at 0° C., thenthe reaction is quenched by addition of tetraethylammonium bicarbonate(TEAB) (1M) (1.5 mL) and water (15 mL). The aqueous solution is washedwith CHCl₃ and ether, then lyophilised. The crude product is purified byHPLC using a C18 column with water and 5% acetonitrile in water toprovide the mono-phosphate as a triethylammonium salt afterlyophilization.

Example 19 5′-p-Phenyl Methoxyalaninylphosphate Prodrugs

To a solution of the appropriate nucleoside compound (0.6 mmol) inanhydrous THF (5 mL) is added phenyl methoxyalaninylphosphorochloridate(40 mg, 5 eq.) (freshly prepared following the literature procedure: J.Med. Chem. 1993, 36, 1048-1052 and Antiviral Research, 1999, '43, 37-53)and 1-methylimidazole (95 μl, 10 eq.) at RT under Ar. The reaction isfollowed by TLC. After 36 h, the reaction mixture is evaporated and theresidue purified on silica gel with 0-10% MeOH in CH₂Cl₂ as eluent toprovide a 1:1 mixture of diastereomers.

Example 20 2-[5-O-Bis (pivaloyloxymethyl)]phosphoryl-prodrugs

To a solution of triethylammonium salt of compound nucleosidemono-phosphate (0.024 mmol) in anhydrous MeOH (0.5 mL) is addedtributylstannyl methoxide (14 jj. L, 2 eq.) at RT under Ar. The reactionmixture is stirred at RT for 30 min then evaporated and co-evaporatedwith acetonitrile three times. The residue is dissolved in anhydrousacetonitrile (3 mL) and tetrabutylammonium bromide (15.5 mg, 2 eq.) andiodomethyl piovalate (58 mg, 10 eq) are added. The reaction mixture isheated at reflux for 1 h cooled to RT, and the solvent is evaporated.The residue is purified on a silica gel column with 1-5% MeOH in CH₂Cl₂to provide the prodrug.

Example 21 Nucleoside 5′-di-phosphates

To a solution of the triethylammonium salt of 5′-mono-phosphate (0.031mmol) [dried by coevaporation with anhydrous DMF twice (2×1 mL)] in 0.5mL of anhydrous DMF is added N,N′-carbonyldiimidazole (25 mg, 5 eq.) atRT under Ar. The reaction mixture is stirred at RT for 4 h after whichanalytical TLC shows no starting material. Then tributylammoniumphosphate salt (1.5 7H-Bu₃N/phosphate, which is prepared (see PCT, WO88/03921) and further dried by coevaporation with anhydrous DMF threetimes) is added to the above solution. The reaction is followed by TLCand typically after 3 days, LC-MS shows significant (>50%) conversion toproduct. The reaction is quenched with 1 mL of triethylamine, 1 mL ofwater, and stirred at RT for 40 min. The crude product is purified byreverse phase HPLC to provide pure product.

Example 22 Nucleoside-5′-tri-phosphates

Referred to Herein as Compound 25

To an ice-cold mixture of nucleoside (0.1 mmol) in trimethyl phosphate(1 mL, anhydrous) was added POCl₃ (30 μl), and the mixture was stirredat 0° C. for 2 h before the addition of Bu₃N (72 μl) followed byacetonitrile (0.5 mL) and tributylammonium pyrophosphate (190 mg). Aftera further 2 h at 0° C., the reaction was quenched by pouring it intoice-cold 1M triethylammonium bicarbonate buffer (10 mL, pH 8.5). Theproduct was purified by preparative HPLC to yield the Compound 25: MSm/z ([M−H]⁻) 519; ³¹P NMR (D₂O) δ −7.4 (m, 1P), −10.1 to −10.2 (m, 1P),−21.1 to −21.3 (m, 1P).

Example 23 Cell-Based HCV RNA Replication Luciferase Reporter Assay

The MP-1 cells for the Cell-Based HCV RNA Replication LuciferaseReporter Assay Protocol include a Huh-7 (human hepatoma) derived cellline that harbors a replicating RNA in the cytoplasm. This RNA, termed areplicon, encodes all of the HCV non-structural proteins (HCV NS2 toNS5B, inclusively) that catalyze the replication of the RNA replicon.Replicon copy number per cell is about 1000 to 5000. The replicon isstably maintained as an episome in dividing cells, and therefore it isimportant to keep the cells in a sub-confluent state and to ensureselection for the replicon by culturing the cells in medium supplementedwith 0.25 mg/ml G418. The entire structural region of the HCV genome isreplaced with a neomycin resistance gene; hence this cell line producesno infectious virus. Moreover, the firefly luciferase gene is fused tothe neo^(r) gene with an FMDV-2A autoprocessing peptide that allows forexpression of both mature luciferase and neomycin phosphotransferasefrom one cistron. Luciferase levels are directly proportional to the HCVRNA levels, and the cell system allows for the evaluation of the potencyof HCV inhibitors in cell culture.

The assay outline includes the following steps on Day 1: (1) Plate cellsat a density of 10,000 cells/well of a 96 well plate and incubate 37°C.; (2) Make compound dilutions; (3) Add compound dilutions to cells;(4) Incubate for 72 h. The assay includes the following steps on Day 4:(1) Perform Cell titer blue assay for cytotoxicity (the assay is basedon the reduction of resazurin (cell titer blue) into a fluorescentproduct, resorufin, in metabolically active cells, and the assay can beduplexed with the assay used for HCV replicon luciferase reporterassay); (2) Perform luciferase assay with the Bright-Glo luciferasesubstrate (Promega) and read luminescence; (3) Process results.

Under this outline, the cell culture includes MP-1 cells (Huh7 cellsmaintaining an HCV subgenomic replicon containing the luciferase-FMDV2A-neomycin phosphotransferase fusion gene). The MP-1 cells aremaintained in Dulbecco's Modified Earle Medium (DMEM) supplemented with10% FBS and 0.25 mg/ml G418. The cells are passaged by trypsinizationand frozen in 90% FBS/10% DMSO. During the assay, the DMEM medium issupplemented with 10% FBS, containing 0.5% DMSO and lacking G418.

Regarding cell plate preparation, on the day of the assay, MP-1 cellsare trypsinised and diluted to obtain 5,000-10,000 cells/70 μl in AssayMedium. Seventy μl (about 10,000 cells) are distributed into each wellof a black 96-well ViewPlate™ (Packard). The plate is incubated at 37°C. in 5% CO₂ until compound addition.

Compound plates are prepared as follows: (1) Add compound (20 mM in 100%DMSO) to assay Medium, lacking G418 to obtain a 60 μM solution and afinal DMSO concentration of 0.5%; (2) Sonicate for 15 min (optional);(3) Filter through a 0.22 μm Millipore Filter Unit (96 well format)(optional); (4) Prepare the final dilution plate in a Deep-well titerplate, in columns 3 to 11 add 400 μl of Assay Medium (containing 0.5%DMSO); (5) Transfer 200 μl of compound solution to column 3 of thedilution plate; the highest concentration (2×) is prepared in column 3;(7) Prepare ⅓ serial dilutions by transferring 200 μl from column 3 tocolumn 4, then from column 4 to column 5, serially through to column 11(no compound is included in column 12).

The test compound is added to the cells by transferring 70 μl from eachwell of the Compound Plate to a corresponding well of the Cell Plate(three columns are used as the “No inhibition control”; nine [9] columnsare used for the nine-point dose response). The cells are incubated at37° C., 5% CO₂ for 3 days.

Under the Alamar blue assay protocol, the assay plates are removed froma 37° C. incubator, and 20 μl of CellTiter-Blue™ Reagent is added. Thecells are incubated in the 37° C. incubator for 3 h. The assay platesare shaken for 10 sec and fluorescence at 560_(Ex)/590_(Em) nm isrecorded. The results are expressed relative to the 100% untreatedcontrol using the following equation: %inhibition=100−[(RFU_(compound)−RFU_(blank)/RFU_(untreated)−RFU_(blank))×100].Alternatively, under the MTT protocol the extent of cytotoxicity isdetermined via metabolism of the vital dye3-(4,5-dimethylthiaxol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). MTT(1 mg/ml) was added to each well and plates incubated for 3 hoursincubation at 37° C. Wells were aspirated, iso-propanol (200 μL) wasadded and absorbance values read at 540/690 nm. Compound concentrationsthat developed 50% cytotoxicity (CC₅₀) were calculated using non-linearregression analysis.

Under the Luciferase assay protocol, the medium is aspirated from theAssay Plate and 50 μl of 1× Glo Lysis Buffer (Promega) previously warmedto room temperature is added. Incubation occurs at room temperature for10 min with occasional shaking. Black tape is placed at the bottom ofthe plate, and 50 μl of Bright-Glo luciferase substrate (Promega)previously warmed to room temperature is added. Gentle mixing follows. APackard Topcount instrument is then utilised using the followingprotocol: Data Mode: Luminescence (CPS); Count Delay=1 min; Count time=2sec. The luminescence determination (CPS) in each well of the cultureplate is a measure of the amount of HCV RNA replication in the presenceof various concentrations of inhibitor. The % inhibition is calculatedwith the following equation: % inhibition=100−[CPS (inhibitor)/CPS(control)×100]. A non-linear curve fit with the Hill model is applied tothe inhibition-concentration data, and the 50% effective concentrations(EC₅₀) are calculated using a computer curve fitting program. Thebiological properties of representative compounds of formula I shownbelow in Table No. 3 were investigated in the cell-based HCV RNAreplication luciferase reporter assay by way of the experimentalprotocol described above.

TABLE No. 3 Cell-Based HCV RNA Replication Luciferase Reporter AssayEC₅₀ and CC₅₀ concentrations. Compound No. Example No. EC₅₀ μM CC₅₀ μM 91 1.3 365 11 2 3.1 >100 12 3 0.22 6.5 14 5 1.4 18.8 15 6 0.0062 0.37 3416 3.8 45

TABLE No. 4 Cell-Based HCV RNA Replication Luciferase Reporter Assay %inhibition at 50 uM. Inhibition at 50 μM Compound No. Example No. (%) 91 99 11 2 97 12 3 99 13 4 97 14 5 100 15 6 100 16 7 99 17 8 98 20 10 1922 12 95 32 15 23 34 16 100 35 17 99 38 17 99

Example 24 Total Cellular Replicon RNA Serial Passage Protocol

The HCV sub-genomic replicon is selected in Huh-7 (human hepatoma) withG418 that maintains a replicating RNA episome in the cytoplasm of cells.HCV replicons that are resistant to a specific inhibitor of HCV RNAreplication can be isolated using a dual combination of G418 and thespecific inhibitor. In order to determine whether inhibitor-resistantreplicon RNA encodes for a stable mutation that confers resistance, thereplicon RNA can be isolated from the resistant cell-line and seriallypassaged into naïve Huh-7 cells by electroporation. Following a newround of selection, a cell population or cell-line with the putativeinhibitor-resistant replicon can be phenotyped with the inhibitor toconfirm that the resistant phenotype genetically maps to the repliconRNA.

The assay outline includes the following steps: (1) Isolate cytoplasmicRNA (Qiagen RNAeasy protocol); (2) Transfect into naïve Huh-7 cells; (3)Select colonies 3-4 weeks; (4) Pick and expand colonies, or establishpooled population of cells. In particular, the total RNA is extractedfrom inhibitor-resistant replicon containing Huh7 cells and cultured ina 10 cm tissue culture plate, using an RNeasy Kit (Qiagen) as per themanufacturer's instructions. HCV replicon RNA copy number is determinedby Taqman® RT-PCR analysis and generally, 10 to 20 μg of total cellularRNA (that contains approximately 1×10⁹ copies of HCV RNA) is transfectedby electroporation into 8×10⁶ naïve Huh-7 cells. The transfected cellsare subsequently cultured in 10 cm tissue culture plates containing DMEMsupplemented with 10% fetal calf serum (10% FCS). Media are changed toDMEM (10% FCS) supplemented with 0.25 mg/ml G418 24 h after transfectionand that is changed every three days. If required, cells are passaged1:3 to maintain the culture sub-confluent. Visible colonies are formedthree to four weeks post-transfection and G418 selection. G418 resistantcolonies may be picked and expanded into second generation cell lines,or pooled into a population culture that constitutes the cells harboringserially passaged HCV Replicon RNA. The passage of mutations that arestable and confer resistance to a specific inhibitor are confirmed bymeasuring EC₅₀ with the second generation of replicon cells.

Example 25 NS5b Chain Termination Assay

The NS5b chain termination assay uses stepwise addition of eachnucleotide complementary to the overhang of a hairpin template, with thefirst nucleotide radioactive, i.e. the direct labelling method. If atest compound is a chain terminator, the system is able to clearly showits incorporation into the chain, and no further extension is observed.

Under this protocol, the contents of two separate vials are prepared.Vial A contains 1.5 μl 10× buffer, 1.5 μl enzyme, 1.0 μl oligo and 5.0μl for a total volume of approximately 9 μl. Vial B contains NTPs of 6μl. The contents of Vial A is mixed with the contents of Vial B toprovide a total volume of 15 followed by incubation at 30° C. for 60min. The aliquot is mixed with RNA loading buffer, heated at 70° C. for15 min and run onto a 20% acrylamide gel with 7.2 M urea. The finalconcentration of NS5b is 1 μM, and the final concentration of NTP/cpd is2 μM.

Example 26 HCV Polymerase Inhibition Assay

Poly r(U) RNA template (Sigma) is employed for the HCV NS5b polymeraseinhibition assay using a NS5bΔ55 (genotype 1b) purified enzyme. Thekinetic constant, K_(m), is determined for the Poly r(U) template andATP using a non-linear, least squares fit of initial rates as a functionof substrate concentration assuming Michaelis-Menten kinetics.

Standard RdRp assays consist of 20 μg/mL Poly r(U) RNA template and 100nM HCV NS5bΔ55 (genotype 1b) in a 50 μl, reaction mixture containing 20mM Tris-HCl, 5 mM MgCl₂, 5 mM MnCl₂, 3 mM DTT, 72 μM ATP, and 0.019 μM[α-³³P]ATP. Elongation reactions are initiated by the addition of ATP,and proceed for 60 min at 25° C. Reactions are quenched by the additionof 0.2 M EDTA, and product formation is collected by filtration throughMultiscreen plates (Millipore). Quantification of product formation wasperformed using TopCount (Perkin Elmer). The inhibitor concentration atwhich the enzyme catalysed rate is reduced by half (IC₅₀) is determinedusing a computer program for curve fitting. IC₅₀ concentrations fornucleoside 5′-triphosphate compounds of the present disclosure areexpected to range from <10 nM to >100 μM. Under these conditions, theIC₅₀ for Compound 25 is 0.37 μm.

HCV NS5b Polymerase K_(i) Determination Assay

A modified method of the NS5b Polymerase inhibition assay was used todetermine the K_(i) and the mode of action for NS5b inhibitor compounds.The enzyme and template were fixed at 100 nM and 20 g/mL and all otherreaction conditions were identical to the NS5b polymerase inhibitionassay. The velocity of NS5b reactions were monitored at different ATPand inhibitor concentrations. The ATP concentration ranged from 0.1 μMto 1000 μM, and the concentration of the inhibitor ranged from 0.003fold to 7 fold of the IC₅₀ value. Velocities obtained at each ATP andinhibitor concentration were analysed using Graph Pad Prism to identifythe mode of inhibition and K_(i) for inhibitor compounds. Under theseconditions, the Ki for Compound 25 is 0.08 μM.

Example 27

In vitro anabolism of Compound 9 in replicon cells and primary humanhepatocytes produces the triphosphate species Compound 25. The structureof Compound 25 is

the synthetic preparation of which is discussed above in Example 22.

In vitro anabolism of Compound 9 and the intracellular accumulation ofits triphosphate (Compound 25) were studied in adherent Huh-7 and platedprimary human hepatocytes. The Huh-7 human hepatoma liver cells(JCRB0403 http://cellbank.nibio.go.jp/) are maintained in DMEMcontaining 10% fetal bovine serum (FBS). Huh-7 cell clones carrying aHCV subgenomic replicon (Lohmann et al., 1999. Science 285: 110-113) aremaintained in DMEM supplemented with 10% FBS and 0.25 mg/ml G418. Thecell lines are grown at 37° C. in a 5% CO₂-95% air atmosphere. Platedprimary human hepatocytes (6-well Collagen/No Overlay) were purchasedfrom Cellz Direct (NC, USA) and maintained in InVitroGro Medium (Celsis,In Vitro Technologies, MD USA) under the same incubation conditions.

For intracellular anabolism studies, Huh-7 cells are trypsinized,harvested, re-suspended in DMEM supplemented with 10% FBS, counted andseeded at a density of 0.7×10⁶ cells per well in a six-well plate andincubated for a period of 24 hr at 37° C. in 5% CO² atmosphere. Media isremoved and replaced with fresh DMEM+10% FBS containing 10 μM Compound 9for a period of 24 hr at 37° C. The cell monolayer is then quicklywashed three times with drug-free medium to remove extracellularCompound 9 and each well is incubated with fresh DMEM+10% FBS for aspecified time period (i.e. 6-wells at 0, 2, 4, 8, 24 and 48 hr). At theend of the incubation period, the medium is aspirated from the well andthe cell monolayer is washed with cold phosphate buffered saline, pH7.4. The washed cell monolayer is treated with 1.0 ml ice-cold 70%methanol:water, scraped and harvested into a centrifuge tube and thensonicated for 1 min at 4° C. The resulting cell lysate is storedovernight at −80° C. and subsequently used to extract the metabolites ofCompound 9. Isolation of Compound 9 and the intracellular metabolites ofCompound 9 from plated primary human hepatocytes uses similarexperimental conditions, except that InVitroGro Medium is used as thecell culture medium.

Sample Analysis for intracellular nucleoside metabolites: The celllysate samples are thawed on ice, and subjected to two freeze/thawcycles in a dry ice/acetone bath. Cells extracts are vortexed andcentrifuged at 16000 g for 5 min at 4° C. and 40 μL of supernatant isinjected for analysis using a API4000 triple quadrupole system. TheShimadzu LC autosampler is set at 4° C. to minimize evaporation.Compound 9 mono-, di- and triphosphate (Compound 25) are separated usinga pH gradient on a Biobasic AX, 3.0×50 mm column maintained at 40° C.The mobile phase consists of solvent A (10 mM ammonium acetate in 30:70ACN/H20 containing 0.008% glacial Acetic Acid) and solvent B (1 mMammonium acetate in 30:70 ACN/H20 containing 0.225% ammonia hydroxide).The elution is performed using a linear gradient of buffer B from 10 to100% in 2.5 minutes, and then held under isocratic condition for 3.0minutes at a composition of 100% B at a constant flow rate of 0.5ml/minute. The mass spectrometer is operated in positive ionelectrospray mode utilizing a multiple reaction monitoring scanfunctionality at m/z m/z 361.1->227.1, 441.1->227.1 and 521.1->227.1 forCompound 9 mono-, di- and triphosphate, respectively. The respectivemetabolites are identified and quantified by comparing theirchromatographic profiles and peak area response with those of authenticstandards.

The pharmacokinetic properties of Compound 9 were determined in maleSprague-Dawley rats, beagle dogs and cynomolgus monkeys (n=3 in eachspecies) with an oral dose of 5 mg/kg and iv dose of 2 mg/kg. PKparameters were analyzed using the WinNonlin noncompartmental model.

As shown in the Table No. 5 below, following 24 hours incubation ofHuh-7-HCV subgenomic replicon cells with 10 μM initial concentration ofCompound 9, the intracellular concentration of Compound 25 reached 5.7μmol/million cells. Unexpectedly, primary human hepatocytes generatemuch higher (˜60-fold) intracellular levels of the triphosphate ofCompound 9 under the same experimental conditions.

Compounds whose plasma half-life is >2 hours, and whose intracellulartherapeutically active anabolite has a half-life of >10 hours areexpected to have a greater potential to be administered once dailytherapeutically. The decay half-life (t1/2) of Compound 25 displays abiphasic profile in both replicon cells and primary human hepatocytes: arapid decay t1/2 (0.59 vs 3.4 hrs), followed by a prolonged slowdepletion with a t1/2 >38 hrs in both replicon cells and primary humanhepatocytes.

TABLE NO. 5 Intracellular accumulation of Compound 25 and its decayhalf-lives in replicon cells vs in human primary hepatocytes (24 hoursfollowing incubation with Compound 9 at the initial concentration of 10μM) Compound 25 Huh-7 cells Human Hepatocytes Intracellular Triphosphate5.7 339 Concentration (pmol/million cells, 24 hr incubation)Triphosphate decay half-life, 0.59 3.4 Initial phase (α, h) Triphosphatedecay half-life, 45 38 Elimination phase (β, h)

As shown below in Table No. 6, cross-species PK of Compound 9 showed anelimination t1/2 ranging 4-7.6 hours, with a oral bioavailability of33-96%. Based on these data, it is expected that the plasma half-life ofCompound 9 in humans will be sufficient for it to be dosed once dailygiven the long-intracellular half-life of its triphosphate and itshalf-lives in different animal species.

TABLE No. 6 Pharmacokinetic properties of Compound 9 following a singleiv (2 mg/kg_(BW)) or oral dose (5 mg/kg_(BW)) in rats, monkeys and dogs.CL Vss C_(max) AUC (mL/min/kg_(BW)) (L/kg_(BW)) t_(1/2) (h) (μM) (μM ·h) F % Rat 18.8 4.19 4.0 2.38 13.0 83 Monkey 20.5 2.43 4.3 0.82 5.0 33Dog 11.4 5.22 7.6 8.36 24.9 96 Abbreviations: CL: total clearance; Vss:steady state volume distribution; T_(1/2): terminal eliminationhalf-life; Cmax: maximum concentration observed following the oral dose;AUC: area under the curve of plasma exposure; F %: oral bioavailability.

Throughout this specification and the claims which follow, unless thecontext requires otherwise, the word “comprise,” and variations such as“comprises” and “comprising,” will be understood to imply the inclusionof a stated integer or step or group of integers or steps but not theexclusion of any other integer or step or group of integers or steps.All patents, patent publications, literature, and references mentionedherein are incorporated by reference in their entirety.

1. A compound of formula I for use in treating or preventing a hepatitisC viral infection in a subject suffering from or at risk of a hepatitisC viral infection comprising in vivo production of a therapeuticallyeffective metabolite of the compound of formula I, wherein themetabolite has an intracellular half-life of greater than about 10hours, and wherein formula I comprises:

wherein the

defines the active pharmaceutical ingredient as a D- or L-nucleoside ornucleotide; A is selected from the group consisting of —O—, —S—, —CH₂—,—CHF—, —CF₂—, and —NR—; R^(1′), R², R^(2′), R³, R^(3′), and R^(4′) areindependently selected from the group consisting of —H, halogen, —OH,—NHOH, —NHNH₂, —N₃, —CN, —OCOCHNC(CH₃)₂, —COOH, —CONH₂, —C(S)NH₂, —COOR,—R, —OR, —SR, —SSR, —NHR, and —NR₂, or R² and R^(2′) together or R³ andR^(3′) together represents ═O, ═S, or =L′-Y′, where L′ is selected fromthe group consisting of N, CH, CF, CC1, and CBr and Y′ is selected fromthe group consisting of H, halogen, N₃, methyl, ethyl, and CN; R isindependently halogen, —H, —OH, —SH, —CN, S(C₁-C₄alkyl), —NO₂, NH₂,—NHNH₂, —N₃, —NR′R′ wherein each R′ is independently H or C₁-C₄ alkyl,—C(S)NH₂, —CH₃, —CH₂OH, —CH₂NH₂, —CH₂NH₃ ⁺, —COOH, —COOCH₃, —COOCH₂CH₃,—CONHCH₃, —CONH₂, —CF₃, —N(CH₃)₂, —NHCOCH₃, —NHCONH₂, —NHCNHNH₂, —ONH₂,—CH₂OCH₃, —O(CH₂)CH₃, COOC₁-C₄alkyl, optionally substituted alkyl,optionally substituted alkenyl, optionally substituted alkynyl,optionally substituted aryl, optionally substituted acyl, optionallysubstituted arylalkyl, optionally substituted cycloalkyl, optionallysubstituted cycloalkenyl, optionally substituted phenyl, optionallysubstituted heteroaryl, optionally substituted heterocyclyl, optionallysubstituted alkyloxy, optionally substituted alkenyloxy, optionallysubstituted alkynoxy, optionally substituted aryloxy, optionallysubstituted acyloxy, optionally substituted oxyacyl, optionallysubstituted arylalkoxy, optionally substituted heterocycloxy, optionallysubstituted heteroaryloxy, optionally substituted cycloalkoxy,optionally substituted cycloalkenoxy, optionally substituted amino,optionally substituted aminoacyl, optionally substituted aminoacyloxy,optionally substituted acylamino, optionally substituted oxyacylamino,optionally substituted oxyacyloxy, optionally substituted acylimino,optionally substituted acyliminoxy, optionally substituted oxyacylimino,optionally substituted aminothioacyl, optionally substitutedthioacylamino, optionally substituted aminosulfinyl, optionallysubstituted aminosulfonyl, optionally substituted thio, optionallysubstituted thioalkyl, optionally substituted thioacyl, optionallysubstituted thioacyloxy, optionally substituted oxythioacyl, optionallysubstituted oxythioacyloxy, optionally substituted phosphorylamino,optionally substituted sulfinyl, optionally substituted sulfonyl,optionally substituted sulfinylamino, optionally substitutedsulfonylamino, optionally substituted oxysulfinylamino, and optionallysubstituted oxysulfonylamino; L is selected from the group consisting—O, —S, —NH, —NR, —CY₃, —CY₂O, —CY₂S, —CY₂NH, —CY₂, —CY₂CY₂, —CY₂OCY₂,—CY₂SCY₂, and —CY₂NHCY₂; Y is independently selected from the groupconsisting of —H, halogen, —R, —OR, and —NR₂; R⁵ is selected from thegroup consisting of —OH, —R, —OR, —NR₂, or a mono-phosphate,di-phosphate, or tri-phosphate moiety or mimic thereof; Base is a groupof formula II:

wherein the

is a single or double bond; Z¹, Z³, and Z⁴ are independently selectedfrom the group consisting of >C—CONHR, >C—CONR₂,>C—C(S)NH₂, >C—COOR, >C—R, >C—OR, >C—SR, >C—NHR, >C—NR₂, >C-optionallysubstituted heteroaryl, >C-optionally substituted alkyl, and >C-G; Z² isselected from the group consisting of >C—NH₂ and >C═O; G isindependently selected from the group consisting of —H, —F, —Cl, —I,—NH₂, —NHCH₃, —CN, —COOH, —CSNH₂, —C≡CCH₃, —C≡CCH₂OH, —C≡C—Si(CH₃)₃,—CONH₂, —CONHCH₃, —CONH-phenyl, —CONH-methylphenyl, thiazole, oxazole,imidazole, imidazoline, triazole, and tetrazole, and when the compoundcomprises two or more G groups, the G's are identical or different; andwhen A is O; R″, R³, R^(4′), and R⁵ are H; L is O; and R^(2′) and R^(3′)are OH; then R² is halogen, OH, NHOH, NHNH₂, N₃, CN, OCOCHNC(CH₃)₂,COOH, CONH₂, C(S)NH₂, COOR, R⁶, OR, SR, SSR, NHR, or NR₂, and R⁶ ishalogen, OH, SH, CN, S(C₁₋₄ alkyl), NO₂, NH₂, NHNH₂, N₃, NR′R′ whereineach R′ is independently H or C₁₋₄ alkyl, C(S)NH₂, CH₃, CH₂OH, CH₂NH₂,CH₂NH₃ ⁺, COOH, COOCH₃, COOCH₂CH₃, CONHCH₃, CONH₂, CF₃, N(CH₃)₂,NHCOCH₃, NHCONH₂, NHCNHNH₂, ONH₂, CH₂OCH₃, O(CH₂)CH₃, COO(C₁₋₄ alkyl),substituted alkyl, substituted alkenyl, substituted alkynyl, substitutedaryl, substituted acyl, substituted arylalkyl, substituted cycloalkyl,substituted cycloalkenyl, substituted phenyl, substituted heteroaryl,substituted heterocyclyl, substituted alkyloxy, substituted alkenyloxy,substituted alkynoxy, substituted aryloxy, substituted acyloxy,substituted oxyacyl, substituted arylalkoxy, substituted heterocycloxy,substituted heteroaryloxy, substituted cycloalkoxy, substitutedcycloalkenoxy, substituted amino, substituted aminoacyl, substitutedaminoacyloxy, substituted acylamino, substituted oxyacylamino,substituted oxyacyloxy, substituted acylimino, substituted acyliminoxy,substituted oxyacylimino, substituted aminothioacyl, substitutedthioacylamino, substituted aminosulfinyl, substituted aminosulfonyl,substituted thio, substituted thioalkyl, substituted thioacyl,substituted thioacyloxy, substituted oxythioacyl, substitutedoxythioacyloxy, substituted phosphorylamino, substituted sulfinyl,substituted sulfonyl, substituted sulfinylamino, substitutedsulfonylamino, substituted oxysulfinylamino, or substitutedoxysulfonylamino; or a pharmaceutically-acceptable salt, ester, solvate,hydrate, or prodrug thereof.
 2. The compound of claim 1, wherein A isoxygen.
 3. The compound of claim 2, wherein L is O and R⁵ is H or themono-, di-, or tri-phosphate moiety or mimic thereof.
 4. The compound ofclaim 3, wherein the plasma half-life of the compound is greater thanabout 2 hours upon administration to a human subject.
 5. The compound ofclaim 4, wherein the compound comprises4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazineor one or more pharmaceutically-acceptable salts, esters, solvates,hydrates, or prodrugs thereof.
 6. A method of treating a subject in needthereof with the compound of claim 1 or 5, comprising administering thecompound once daily to the subject.
 7. The compound of claim 5, whereinthe compound has a cross-species plasma elimination half-life (t1/2)ranging from 4 to 7.6 hours and an oral bioavailability ranging from 33to 96%.
 8. The compound of claim 5, wherein the metabolite is4-amino-7-(2-C-methyl-β-D-ribofuranosyl)-pyrrolo[2,1-f][1,2,4]triazine5′-triphosphate and has the structure


9. The compound of claim 8, wherein the metabolite has an intracellularhalf-life of ≧38 hours in primary human hepatocytes.
 10. A composition,comprising: the compound of claim 1 or 5; and one or more compoundshaving anti-HCV activity.
 11. A pharmaceutical dosage form, comprising atherapeutically effective dose of a compound of formula I of thestructure:

wherein: R″ is H, F, Cl, I, CN, CONH₂, C≡CSi(C₁₋₄ alkyl)₃, C≡CH, COOH,CSNH₂,

R² is C₁₋₄ alkyl, and R⁵ is H,

or a mimic thereof, a salt, ester, solvate, hydrate or prodrug thereof,and one or more pharmaceutical carriers, diluents, or excipients. 12.The pharmaceutical dosage form of claim 11, wherein R″ is H, R² is CH₃,and R⁵ is H or


13. The pharmaceutical dosage form of claim 12, comprising atherapeutically effective dose of an active pharmaceutical ingredient ofthe structure:

or, a salt, ester, solvate, hydrate or prodrug thereof, and one or morepharmaceutical carriers, diluents, or excipients.
 14. The pharmaceuticaldosage form of claim 13, wherein the pharmaceutical dosage form isadapted for once daily dosing.
 15. A pharmaceutical dosage form for usein treating a hepatitis C viral infection by administering to a subject,once per day, said pharmaceutical dosage form comprising atherapeutically effective amount of a compound:

and one or more pharmaceutically acceptable carriers, diluents, orexcipients.
 16. The pharmaceutical dosage form of claim 13 or 15,wherein a therapeutically active dose is in the range of about 10 μg/kgto about 30 mg/kg.
 17. The pharmaceutical dosage form of claim 13 or 15further comprising a hydrochloride salt of an active pharmaceuticalingredient.
 18. The pharmaceutical dosage form of claim 13 or 15 furthercomprising an ester of an active pharmaceutical ingredient.
 19. Thepharmaceutical dosage form of claim 13 or 15 further comprising aprodrug of an active pharmaceutical ingredient.
 20. The pharmaceuticaldosage form of claim 13 or 15, wherein the dosage form comprises anoral, a rectal, a nasal, a topical, a buccal, a sublingual, atransdermal, a vaginal, an injection, or a parental dosage form.
 21. Thepharmaceutical dosage form of claim 20, wherein the pharmaceuticaldosage form is an oral dosage form.